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Pre-Empt FAQ


We have been receiving a lot of questions about Pre-Empt. He are some responses to the common questions:


When is Pre-Empt appropriate?

It is best suited for recirculating hydroponic production of leafy greens. It can be used as a direct substitute for conventional fertilizers in NFT, DWC/Floating Raft, and Flood & Drain. When used properly, it won’t clog 1/4″ emitters which is very rare for an organic fertilizer.

When is Pre-Empt not appropriate?

The cost may be prohibitive for drain-to-waste systems. We do not have any experience with the product being used in aeroponic or aquaponic systems.

Can Pre-Empt be used for tomatoes?

Yes, but…
-Growth may be overly vegetative and not as reproductive as standard commercial tomato formulas
-Blossom end rot will likely be an issue on larger varieties like beefsteaks
-Works well with grape and cherry tomatoes but still may have overly vegetative growth
-Calcium may be supplemented with an organic solution grade gypsum

What amendments would you suggest to use with Pre-Empt?

-Organic solution grade gypsum and silica may be used to reduce tip burn or blossom end rot
-Inoculants like TerraBella can help reduce biofilms and improve nutrient availability

How do I inoculate a tank with beneficial microbes?

Fill a 5 gallon bucket with water and add 1 oz molasses. Let water sit for 1 day to remove chlorine (unless using RO or distilled water). Add 2 oz. of TerraBella and let sit for 1 day before adding to reservoir. This is enough to inoculated 300 gallons of nutrient solution.

How often should I change the reservoir?

This is going to vary a lot depending on growing environment, system, water source, and fertilizer rate. In general, using a water source with a very low EC and keeping the fertilizer rate low will help extend the life of the reservoir. Some growers flush their system once every 4-5 months and some growers flush every two weeks. The cost to build a reservoir with Pre-Empt may be up to 100x more expensive than conventional fertilizers so it is very important to reduce the frequency of flushes.

What EC should I maintain?

This will depend on source water EC and crop. The target EC is generally going to be lower than the EC used with conventional fertilizers. Generally leafy greens are grown at an EC ranging from .8 up to 1.6. It is best to start low to avoid the development of biofilms in the system

What pH should I maintain? And how?

I’ve seen growers completely ignore pH while using Pre-Empt. The pH may fluctuate from 4.8 up to 7.5 without noticeable effect on the crop. I’ve also seen growers maintain pH levels with citric acid and sodium bicarbonate.

How consistent is Pre-Empt from batch to batch?

There is variability in the product and it is possible that a batch may perform differently than previous batches. This variability is generally minimal enough that growers do not need to adjust practices.

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Why should you attend the International Congress for Controlled Environment Agriculture 2017? – Part 2

As I posted earlier this month, I have been fielding a lot of questions from industry peers asking why Hort Americas continues to support, sponsor and have a booth at the 2nd International Congress on Controlled Environment Agriculture (ICCEA). This event is scheduled for May 17-19, 2017, in Panama City, Panama. I thought the best way to respond was to write a two-part blog. In my first post I focused on my business reasons for participating in ICCEA. In this second post I will focus on my philosophical reasons for my involvement with ICCEA.

Education is the foundation for innovation

I firmly believe in education. I believe that kids who have access to the best educational opportunities have a huge head-start.

I believe those young adults who are fortunate enough to attend and disciplined enough to commit themselves to a college education give themselves the opportunity to develop skills and have experiences that provide them with advantages over their peers. Business people committed to constantly challenging and questioning themselves on what they think they know through continuing education have the opportunity to be the leaders and innovators who reshape their perspective industries.

This is why I am committed to ICCEA. ICCEA is about education. ICCEA is about bringing together the best and brightest minds so that they can share their research and experiences. ICCEA is committed to expanding the knowledge base of its attendees. Each of these attendees will return to their businesses knowing they are armed with the best base of horticultural science information currently available.

For those of you who know me, my commitment to education as the base for a solidpersonal and professional foundation should not surprise you. For those of you who don’t know me, I ask that you visit the Hort Americas website, read the back issues of Urban Ag News and their blogs. You will quickly realize that my companies and I are not only committed to continuously educating and learning, but also to supporting those committed to horticultural and agricultural extension services.

Networking is an opportunity to explore

Whenever you meet successful business people, they usually have a diverse network of professional associates. This should not be a surprise as part of their success is their vast network of knowledgeable colleagues and friends. These networks allow them to easily navigate the business challenges and obstacles they encounter daily.

Because “good” networking leads to opportunities that create success for both parties these relationships are often long lasting and they (at least in my case) lead to some amazing friendships. This is another reason I firmly believe that networking is not selling.

Networking is listening and learning. Networking provides assistance when opportunities present themselves. In some cases these opportunities lead to sales, but effective networking does not have to lead to a business transaction.

How networking has impacted me

I credit education and networking with putting me where I am today professionally (and personally.) There are many people responsible for making me who I am today. In addition to my family and friends, many of the people I credit with helping me develop as a horticultural professional I met at educational events throughout my career. Three of these industry colleagues (and friends) will be at ICCEA this year:

1. Dr. Don Wilkerson, Texas A&M University horticulture professor and extension specialist emeritus

I met Don when I was a young “professional” more concerned with having a great time over anything else. Unfortunately I cannot share the stories of my younger years, and hopefully Don won’t either. But, that simply shows you how good of an educator Don is.

Unknowingly Don was able to communicate commercial horticultural issues in a way that made it easy for me to understand. More importantly Don inspired me to ask questions that I sought the answers for.

2. Dr. Toyoki Kozai, professor emeritus and chief director, Japan Plant Factory Association Center for Environment, Health and Field Sciences at Chiba University

Dr. Kozai graciously opened himself up to an American who had never been to Japan. I had a long list of questions for him and I was eager to learn anything and everything I could about vertical farming. Whether the questions were from me or anyone else I have seen Dr. Kozai interact with, he always takes the time to answer every question, no matter how elementary, with respect and care.

3. Dr. Chieri Kubota, professor, University of Arizona, The School of Plant Sciences, Agricultural and Biosystems Engineering

A former student of Dr. Kozai, Chieri likely does not know this, but I totally enjoy visiting with her. Not because she is always willing to share new facts and figures based on her research, but because she is so excited about her work that she inspires me to continue to be passionate about our industry.

After reading the two blogs I have prepared on ICCEA it should be obvious why Hort Americas will be attending this industry event in Panama City, Panama, on May 17-19, 2017. During this conference we will be there learning from leading horticulture researchers, networking and creating opportunities with government representatives, existing agricultural/horticultural businesses, entrepreneurs and manufacturers of controlled environment agriculture products.

Look forward to seeing you in Panama.

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Why the International Congress for Controlled Environment Agriculture 2017? – Part 1

Recently I have been fielding a lot of questions from industry peers asking why Hort Americas continues to support, sponsor and even have a booth at the 2nd International Congress on Controlled Environment Agriculture (ICCEA). This event is scheduled for May 17-19, 2017, in Panama City, Panama. I thought the best way to respond was to write a two-part blog posting. In my first post I will focus on my “business” reasons and in the second post I will focus on my philosophical reasons.

Business opportunities in developing markets

As we all know, “the only constant is change.” This is no different in the world of commercial agriculture and production horticulture regardless of geographical locations. Panama and other Latin American countries have a very strong and proud history in agriculture and horticulture, which due to changing weather patterns are being forced to adapt. As one would expect, these changes will not come easy and will cause many farms, of all sizes, to suffer in the process. If these same farms want to continue operating and more importantly want to continue to be profitable, they will need to find a new way. My belief is that controlled environment agriculture (CEA) can and will be one of the tools that help these farms redefine themselves.

CEA is a technology-based approach to food production. The aim of CEA is to provide protection and maintain optimal growing conditions throughout crop development. Production takes place within an enclosed growing structure such as a greenhouse or building.

Panamanian government officials feel the same way. They have shown and continue to show a commitment to helping the country’s farmers.

The government’s support started in 2015 and 2016 when it committed and put to work approximately $100 million USD towards investments in innovative production techniques and strategies. In January 2017 the government announced a first-round monetary infusion of $243 million USD for fiscal year 2017 to be directed toward increasing food production using controlled environment/precision agriculture. These funds will be used to transition from current traditional agriculture and its challenges, including water, inputs, available arable land, to technology-based food production which includes CEA.

Panama funds CEA projects

Hort Americas has seen Panama’s government funding put to work. In the last 18 months the following projects have either been initiated or implemented.

* 10 Greenhouses of various sizes built with all the necessary equipment/technology.

* 2 Indoor farm food production facilities (one currently in development stage).

* 1 New university research-and-development facility.

* 1 Tissue culture laboratory.

* 1 CEA seedling production facility.

* 4 Private research-and-development facilities to test indoor food production (agricultural companies).

The following projects are currently in the planning stage.

* 1 Large-scale, world class research-and-development facility (a combined private/government/university initiative).

* 5 Greenhouses (more possible with new incentives recently announced).

* 1 Indoor food production facility.

Panama is one of several Latin American countries receiving this type of financial funding to upgrade the agriculture sector. Peru, Chile and other countries are following suit. In addition, there is a robust effort by CAF Development Bank of Latin American, and other multilateral organizations to increase their agriculture portfolio throughout Latin America, applying technology to produce food.

Hort Americas’ customers are active in the production of food and flowering crops using the technology that best fits their region. From our perspective, and depending on the crops, CEA can be designed and built to suit a variety of crops, production methods and management styles. This can be done as a greenhouse, vertical farm/plant factory or tissue culture facility.

ICCEA does two things to support CEA. First, it focuses on the education needed to support crop production regardless of the technology or geographic region. Second, it brings together people with varied backgrounds, including international investors, growers/farmers, innovators and entrepreneurs.

Due to ICCEA’s unique program and approach it not only attracts attendees from Latin America, it also attracts creative and innovative minds from around the world. In 2015, Hort Americas was amazed to meet and develop working relationships with many new businesses from the United States and Canada.

Unprecedented opportunities for everyone.

ICCEA creates opportunities for people and companies to build business partnerships. And that is what we look for–opportunity. When people have access to information and science that supports what they are interested in, good things happen. When people have the opportunity to listen to leaders from their industry, good things happen. When people have the opportunity to share great food and drink, good things happen. When people have the opportunity and time to professionally network, good things happen.

In 2015, Hort Americas had the pleasure of meeting and starting new business relationships with many new people and companies from the USA, Canada and the Caribbean (arguably more developed markets.) These attendees represented a wide array of thought, businesses, hydroponic crops and experience. It was awesome. Based on conversations we are currently having, we see even more opportunities to meet new and existing customers in 2017.

So, once again Hort Americas will be attending ICCEA in Panama City, Panama, on May 17-19, 2017. We will be there learning from leading researchers, networking and creating opportunities with government representatives, existing agricultural/horticultural businesses, entrepreneurs and manufacturers of CEA products.

Stay tuned for part 2 and hope to see you there.

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Looking for a better, easier way to do greenhouse IPM?

Greenhouse Scout is an integrated pest management app that makes it easier to collect, store and analyze scouting data along with identifying insect pests and which beneficials can be used to control them.

Most greenhouse growers know the benefits of scouting their crops for pest insects and mites. Scouting can help to identify and minimize pest outbreaks, reduce plant damage and crop losses and save on pesticide and biological control costs.

Greenhouse Scout mobile app developed by the New York State Integrated Pest Management Program at Cornell University initially began as a how-to notebook for greenhouse ornamental plant growers.

“Incorporating beneficial organisms for insect and mite management in greenhouses is not something that growers can just jump into,” said Elizabeth Lamb, ornamental IPM coordinator at NYS IPM Program. “A lot of information is required for someone trying to successfully do biocontrol. Once it becomes part of the production system it can work, but getting started is the hard part. We didn’t see one good way of putting all of the information together in a relatively easily accessible format.

Elizabeth Lamb, ornamental IPM coordinator at NYS IPM Program, worked with GORGES Inc. to develop the Greenhouse Scout app.
Photos courtesy of NYS IPM Program

“We initially started putting the information together in a notebook. We said this is great, but we knew people weren’t going to carry the notebook into the greenhouse. When we started asking growers if they would like this as an app, something they could carry on their smart phones, we received a lot of positive responses. That’s how we decided to develop the app.”

Developing an interactive app

NYS IPM Program staff began working with GORGES Inc. in Ithaca, N.Y., to develop the app program. The funding to create the app came from a USDA National Institute of Food and Agriculture grant.

“The company asked me during the initial discussion if we wanted to make the app interactive so that is when we decided to add the scouting and record keeping functions. The app really has two applications. In addition to the scouting function, it’s a source of information for pests and pest identification and for beneficials identification and usage. Even if a grower is not using the app to collect scouting data, it can be used to identify common greenhouse pests like green peach aphid. The app will also determine what beneficials can be used, how to apply them and the environmental factors that need to be considered. All of that information is available on the app.”

Although the Greenhouse Scout app was developed for greenhouse ornamentals, it has application to other protected environment crops.

Lamb said that even though the app was initially developed for greenhouse ornamentals, it could be used with greenhouse vegetables and other protected environment crops.

“The app is specialized by insect pest,” she said. “Anyone who has these insect pests potentially could use the app. For the most part, many of the insect pests we see in ornamental greenhouses are also found in vegetable greenhouses. For vegetable greenhouses a grower could certainly use the app because many of the insect pests and biologicals are the same. We can also add new insect pests and beneficials as they become important.”

More effective scouting

Lamb said even though growers are good about identifying pest problems on their plants, they can have a difficult time tracking the data, especially from year to year.

“We are trying to help growers make scouting easier so that they will do a better job of scouting,” she said. “If a grower is walking through the greenhouse and sees something, he can easily take out his smartphone, go to the app and put that information in. If a grower is doing more organized scouting, the app can be set up to do scouting in specific locations. If there are multiple scouts collecting information all of that data can be inputted simultaneously.”

One of the biggest scouting gaps the app can help eliminate is determining the effectiveness of pesticide and/or beneficials applications.

“At the same time the app is used to note numbers of pest insects and beneficials, it can also be used to record applications of beneficials or pesticides,” Lamb said. “While the app does not include recommendations on what pesticides to use to manage a particular pest, those active ingredients labeled for New York State are listed.”

Although scouting information is being written down on paper or in a notebook, Lamb said having all of this data doesn’t indicate whether beneficials and pesticide applications are working.

“Growers might have a general idea if they are seeing fewer or more of a particular pest from the previous week,” she said. “The app offers growers the ability to look at the scouting data on graphs so they can see whether the pest numbers are going up or down. This gives growers more information to use in terms of deciding what to do.

“We are hoping to reduce pesticide applications by encouraging the use of biological controls. However, if growers are using the app to scout and are only applying pesticides, we would hope that they would also be able to reduce their pesticide use. Growers can use the app’s graphs to determine a pesticide’s effectiveness so that they don’t over apply. If a pesticide is not particularly effective, growers can come back and apply something else.”

Greenhouse Scout offers growers the ability to look at scouting data on graphs so they can see whether pest numbers are going up or down and whether a control application is effective.

Lamb said being able to print the graphs enables growers to keep a running record of what has happened with their crops in previous years.

“Growers can see if there is a pattern for a pest,” she said. “Whether a pest keeps coming in at the same time on the same crop. Growers usually remember those kinds of things, but it’s nice having a resource they can refer to to see what controls actually worked.”

Ease of use

Lamb said the app was designed to be used in all size greenhouses.

“If growers have an internet connection the recording of the scouting data to their computer is automatic,” she said. “If growers don’t have an internet connection in the greenhouse, the app holds the information until the connection is made. It doesn’t have to be plugged into something else. The data is synced directly into the computer. If there are four workers scouting simultaneously in different greenhouses, they can input data on the same account. Growers could sit in their offices looking at what is going on with pest management in all of those greenhouses at the same time.

“The only thing growers need to add is their locations. A location could be designated as Greenhouse 1, Section 1, Bench 1. In some cases growers move their crops around and five different crops may move through that area during the production season. In that case, it might make more sense to call a crop by its name such as pansies. Pansies may move from Greenhouse 1 to Greenhouse 2 and then they move onto sales. The intention was to make the app as flexible as possible. Growers can use the data from year to year if it’s something that makes sense for their operation.”

Lamb said she has received requests to translate the Greenhouse Scout app. She is currently working with GORGES to find out the costs involved with translating the app into Spanish and French. She is also working on apps for conifers and greenhouse hops that will include both insect and disease pests.


For more: Elizabeth Lamb, NYS Integrated Pest Management Program, Cornell University, Ithaca NY 14853; (607) 254-8800;;
NYS IPM’s Greenhouse Scout is available for $9.99 at the Android and iPhone app stores.

David Kuack is a freelance technical writer in Fort Worth, Texas;

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Hort Americas now distributing Sudlac

Sudlac goes for growth

Sudlac is coming to North America in 2017. The company’s goal is to become the leading manufacturer of shading materials for the global greenhouse horticulture market. This is apparent from the complete restyling of the company brand all the way to the development of its fast-growing team. Behind the scenes, every team member is working hard to build a solid, full-coverage distribution network.

Sudlac’s target group is a large segment in the shading market including growers who choose no-nonsense, reliable, high quality shading products. Sudlac is serving this market with a wide range of products from powder in bags to high tech removable coatings in buckets.

Providing excellent service

Sudlac’s updated approach is practical and service-driven. Last year, the company opened a dedicated sales office in Purmerend, Netherlands, which is close to the international Schiphol Airport and the country’s greenhouse cultivation zone. This enables Sudlac to provide excellent support and service in the Netherlands and worldwide.

“The new office better highlights our presence in the Dutch market,” says Export Manager Jorien Plak-Schouten. “This is the base from which we work and provide support with our sales team. We see worldwide opportunity for our shading products. This is why the Dutch team was reinforced with two new account managers, Ruben Lensing and Michel Seignette.”

A well-trained network of distributors supports product deliveries. There are still opportunities for new distribution partners who want to be part of this positive development.

“Throughout the years, we have gained extensive experience, developing our products such that a distributor can include them in their product selection with full confidence,” says Plak-Schouten.

Sudlac also provides support for product application by utilizing the knowledge and experience of Dutch contract applicators, which can be shared with growers worldwide. These applicators can advise from their practical perspective, sharing the best and most professional application methods with growers.


Fresh new look

Sudlac’s website, packaging, brochures and newsletters are vibrant and informative. The product wizard on the new website assists growers step-by-step in selecting the most appropriate product for the relevant crop, location and greenhouse type. The company’s monthly newsletter highlights interesting information related to products as well as practical experiences.

Sudlac’s new style will be presented officially during various horticultural trade shows in January and February 2017. Trade show visitors can experience the fresh new look and be introduced to the company’s extensive sales team.



Sudlac Eclipse LD

Eclipse® LD is a removable white shading paint for greenhouses. It protects crops against too much light and heat throughout the season and can be applied on the outside of all standard greenhouses. Eclipse LD needs to be mixed with water and can be applied in many situations, making it a basic yet all-round product for horticulture use worldwide. Eclipse LD is highly wear-resistant and easily removed with Topclear at the end of the season.

 – Optimal protection of your crops
 – Adjustable shading intensity
 – Wear-resistant
 – Applicable to all greenhouses
 – Removed with Topclear
 – For all greenhouse surfaces

Why Eclipse LD?
The Eclipse LD shade layer reduces stress and prevents crops and fruits from sunburn, improving production and quality. In countries with a moderate climate, Eclipse LD is mainly used for protecting ornamentals and leaf vegetables in greenhouses. In warmer areas of the world, Eclipse LD is also used for fruit vegetables like tomatoes and sweet peppers.
Eclipse LD is a very efficient and versatile shading agent that reduces the light and temperature in the same ratio. This shading product is flexible in use because you can adjust the number of buckets, amount of spray solution and application method. Eclipse LD is easy to apply and to remove.

Eclipse LD needs to be diluted with water before spraying it onto the greenhouse. Depending on the application method, type of greenhouse and climate, the dilution rate and amount of spray liquid can vary to achieve the best results. Eclipse LD can be applied manually, by machine and by helicopter. See how to use for more detailed information about applications and dosage.

Eclipse LD can be removed with Topclear whenever necessary. Apply Topclear in the advised amount and dilution. Read the complete instructions on how to use Topclear.


Sudlac Transpar

Transpar® is a removable shading agent based on a special pigment that reflects heat radiation very efficiently, while maintaining high photosynthetic light levels. Transpar diffuses incoming light which is beneficial in optimizing the greenhouse climate. It is very wear-resistant and can be applied on the outside of all standard greenhouses. Transpar is easily removed with Topclear at the end of the production season.

 – Minimum light shading, maximum heat shading
 – High diffusion rate
 – Applicable to all types of greenhouses
 – Wear-resistant
 – Removed with Topclear
 – For all greenhouse surfaces

Why Transpar?

High solar radiation means high photosynthetic light levels for photosynthesis. However, it also generates heat radiation which can be stressful to crops. Compared to traditional whitewash coatings, Transpar ensures a higher photosynthetically active radiation (PAR) while the heat radiation (NIR) is partly reflected.

Higher PAR results in more photosynthesis. Photosynthesis is the process where the plant energy from the sunlight transfers into sugars. These sugars are the building blocks for plant growth, fruit production and flower quality.
Heat radiation is not used by the crop for photosynthesis. This radiation heats the greenhouse and the crops leading to plant stress. By reducing the heat radiation in the greenhouse, plant temperature is more moderate, resulting in better quality plants and higher production.

In addition to increased PAR transmission, Transpar has great diffusing properties. This improves the greenhouse climate, resulting in positive effects on the quality and production of the crop.

Transpar needs to be diluted with water before application to the greenhouse. Depending on the application method, type of greenhouse and climate, more or less water and buckets should be used to achieve the best results. Transpar can be applied manually, by machine and by helicopter. See how to use for more detailed information about applications and dosage.

Transpar can be removed with Topclear whenever necessary. Apply Topclear in the advised amount and dilution. Read the complete instructions on how to use Topclear.


Sudlac Optifuse IR

Optifuse® IR is a removable greenhouse coating that scatters the light to a high degree in combination with effective heat protection. Optifuse IR is very wear-resistant and can be applied on the outside of all standard greenhouses. Optifuse IR is easily removed with Topclear at the end of the season.

 -High light transmission
 -High diffusion rate
 -Reduces temperature
 -Improves quality and production
 -Removed with Topclear

Why Optifuse IR?
Optifuse IR offers a very high level of diffusion and a high light transmission in combination with an effective temperature reduction. This combination will ensure more photosynthesis and lower greenhouse temperatures.

The incoming light is scattered by the diffuse coating layer, reaching the leaves from top to bottom and from all sides of the crop. This will improve the photosynthesis and transpiration rates of all plant leaves, resulting in better humidity, temperature and CO2 levels inside the greenhouse. It is proven by research that diffuse light in combination with heat reduction has a positive effect on crop production, quality and growth.

Compared to Optifuse, this Optifuse IR version reflects heat radiation (NIR) very efficiently while maintaining photosynthetically active radiation (PAR) transmission.

PAR is the spectral range of solar radiation from 400 to 700 nanometers that crops use for photosynthesis. NIR is the spectral range of solar radiation from 700 to 2,500 nanometers that is very efficient for generating warmth in the greenhouse. NIR is not used by the crop for photosynthesis.

Optifuse IR needs to be diluted with water before spraying it onto the greenhouse. Depending on the method of application, type of greenhouse and climate, more or less water and buckets should be used to achieve the best result. Optifuse IR is best applied by machine to get an even layer for optimum diffusion. See how to use for more detailed information about applications and dosage.

Optifuse IR is removed with Topclear whenever necessary. Apply Topclear in the advised amount and dilution maximum three days before considerable rainfall.


Sudlac Topclear

Topclear removable coatings cleaner

For removing Eclipse LD, Transpar, Optifuse and Optifuse IR

Topclear is the cleaner used to remove Sudlac coatings Eclipse LD, Transpar, Optifuse and Optifuse IR. By using Topclear, a grower has full control over when the coating is to be removed.

 – Easy to apply
 – Dilute with clean water


Mix Topclear with the necessary amount of clean water. Apply the solution evenly onto a dry greenhouse surface under dry weather conditions and a minimum temperature of 5°C (40°F).
Minimal reaction time is 20 minutes before rinsing with water or brushing. Considerable rainfall will wash away the coating. Only apply Topclear if considerable rainfall is expected in the next few days. Removal of Topclear with roof sprinklers is not recommended.

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P.L. Light Systems’ HortiLED series of grow lights meets the requirements of controlled environment agriculture

Whether greenhouse, vertical farm or warehouse growers are propagating or producing ornamental, vegetable or cannabis crops, P.L. Light Systems offers the LED fixtures to meet their lighting needs.

P.L. Light Systems develops and manufactures supplemental lighting systems for the horticultural industry. The nearly 40-year-old company manufactures traditional light sources, including high pressure sodium (HPS) and metal halide, as well as its own light emitting diode (LED) fixtures.

“There are a lot of lighting products hitting the market right now, especially when it comes to LEDs,” said Eric Moody, P.L. Light Systems western USA Lighting Solutions Specialist. “The future of the horticultural lighting market is moving toward LEDs as the technology continues to advance. Every week it seems like there is another company entering the horticultural lighting market. Growers need to carefully look at the lighting companies they are considering working with. How long has a company been around and is it focused on horticulture or is it just buying circuit boards and selling them as LED horticulture lights?”

Even though P.L. Light Systems has been marketing horticulture grow lights for nearly 40 years, it was not one of the first companies to offer LED lights. “One of the reasons that we weren’t one of the first companies is because of the intensities and efficiencies of LEDs,” Moody said. “In 2014-2015 the market started to see LED diodes that could deliver 2.1 micromoles per joule (μmol∙J–1). When this occurred everyone that was selling LEDs to the horticulture industry got excited.

“Double-ended HPS lamps that are used in horticulture put out 2,100 micromoles per 1,000 watts, which is 2.1 μmol∙J–1. So what happened is LEDs finally equaled HPS. LEDs didn’t surpass HPS. When this happened P.L. started looking into the LED market and to surpass what was available.”

P.L. Light Systems’ HortiLED TOP and HortiLED INTER fixtures are finalists in the Horticultural Lighting Category for LEDs Magazine’s 2017 Sapphire Awards. The awards will be presented March 1, 2017, in Anaheim, Calif.


P.L. Light Systems HortiLED TOP

P.L. Light Systems HortiLED TOP light is a fully enclosed fixture with an integrated driver that delivers 2.7 μmol∙J–1. The TOP fixture measures 38 inches long by 4.7 inches wide by 3.7 inches tall and weighs 18 pounds. The fixture is available in two distribution angles, 80º and 150º, and light spectrum of red/blue, red/white, full spectrum and customized.

“P.L. started in the greenhouse market so we are catering to that segment of the market even though there are a lot of indoor growers using our fixtures,” Moody said. “We want to be sure everything we manufacture is able to be used in a greenhouse.

PL Light Systems HortiLED toplighting

“The TOP fixture drivers are driving the diodes to 2.7 μmol∙J–1. But the diodes we are using are capable of going above 3 μmol∙J–1. We are driving our diodes to a lower percentage because we don’t want to overheat them and we want them to last for 28,000 hours. We are better able to control the heat by not overdriving the diodes. Our goal is to have totally passive cooling so the fixture can be hung right up under a truss and it is fully enclosed.” Moody said having a totally enclosed fixture offers an advantage over other toplight LEDs on the market.

“Other manufacturers are either installing fans in their fixtures or they are mounting the drivers separately,” he said. “The LEDs with fans built into the fixtures can suck in dust and insects. These fixtures can short out because they get a build-up of debris inside the fixture. The fans push air across an electrical circuit board. There are also water-cooled fixtures. There is a water line running from one fixture to the next.

“Other manufacturers’ fixtures are large units in order to get the light output. These fixtures might work for some indoor growers, but they’re not going to work in a greenhouse. These larger fixtures reduce the amount of sunlight reaching the plants by casting shadows over them.”

Moody said with LEDs the light is very directional so it doesn’t cover as big of a footprint as HPS.

“We offer two TOP light LEDs that have different distribution patterns,” he said. “It’s not a reflector, it’s the diode itself. We have an 80º diode which is very common. This fixture puts out an 80º wide distribution pattern. We also have a 150º diode that puts out a much wider distribution pattern. This enables us to cater light plans to the growers’ crops. It offers a lot of room to move up and down depending on how far the fixtures need to be from a crop.”


P.L. Light Systems HortiLED INTER

The HortiLED INTER fixture is made for tall vine vegetables, ornamentals and some cannabis production. “The fixtures are mounted down the center of the crop,” Moody said. “It is supplementing the light that is being received from above the crop. For a 14-foot tall greenhouse tomato crop a grower may have HPS or LED toplights above and then the interlights below. Sometimes growers will use two rows of interlight fixtures in order to get more light deeper into their crops.

“The INTER fixture has the same high output diode as our TOP fixture, but because of the cover on the INTER fixture, the output reaches 2.5-2.6 micromoles per joule depending on the light spectrum.”

The INTER LED is a fully enclosed fixture equipped with a polycarbonate cover that keeps it totally waterproof. Moody said this ensures that the fixtures are not affected by high humidity environments, mist systems and spray applications.

The INTER fixture measures 48 inches long by 2.2 inches wide by 4.8 inches tall and weighs about 4 pounds. The fixture operates with an external driver and is available with a red/blue spectrum.

“With an interlighting fixture hanging in the crop, the light distribution pattern should go out to the sides hitting all of the leaves that are around the fixture,” Moody said. “Our INTER fixtures put out what looks like a butterfly wing pattern. The light pattern goes out sideways, but at the same time it also goes down. We use reflector technology to direct the light.

“The INTER fixture has one bank of LEDs. Some other interlight fixtures are larger and heavier units because they have two LED circuit boards back-to-back putting light out on each side of the fixtures.”

Eight of the 4-foot INTER fixtures can be run together using one driver. Moody stated interlight fixtures need to be lightweight because growers hang them on crop wire or whatever is being used inside the crop.

The INTER fixture is not yet available for the U.S. market. “We are still finalizing our UL listing in the U.S. for the INTER fixture,” Moody said. “This fixture is available in the red/medium blue spectrum. The INTER fixture is expected to be available for the U.S. market by the end of the first quarter.”


P.L. Light Systems HortiLED MULTI

The P.L. Systems HortiLED MULTI fixtures are being used primarily for propagation, young plant production and vertical farming.

“Just like with the TOP fixtures, our MULTIs are available in 80º and 150º distribution outputs,” Moody said. “We also have two different lengths, basically a 4-foot (122 cm) and 5-foot (152 cm) fixture. These fixtures have an integrated driver and are available in low and high output versions. There are some applications where a low output is needed, better uniformity, closer to the crop like with tissue culture and early plant propagation applications. The high output fixture is for later in propagation or for propagation of bigger plants. For the MULTIs we can do numerous light spectrum combinations.”

Moody said the MULTI fixtures are ideal for vertical farming applications. “We can do vertical growing with lettuces, mixed greens, microgreens, all of those under these lights as well. Our MULTI lights have a higher output than most other LEDs used for this application.


“For propagation most growers use multiple layers. Typically they are built with two to four layers on racks. The MULTIs were designed to be installed on the underside of a rack pointing down toward the crop below it, from 9 inches to as far away as 2 feet from the crop.”

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GE Lighting horticultural LED lights are specifically designed for controlled environment agriculture


GE Lighting has introduced LED grow lights for use in greenhouses, vertical farms, tissue culture labs and growth chambers.

GE Lighting has been offering horticultural LED lights to the North American market since 2011.

“GE had been marketing horticultural LED lights in Japan prior to introducing them to the United States,” said Sharee Thornton, Product Manager at GE Lighting. “The reason for not introducing them sooner was the U.S. horticulture market was just starting to work with LEDs and GE was still developing the products specific to this market. We currently have three LED products that we are actively selling in the North American market and have additional products that are expected to come out during 2017. These would include interlighting and toplighting products.

“We have customers who operate vertical farms that are asking for a toplighting product. We are developing toplighting products for both vertical farms and for greenhouses.”

horticultural LED grow lights

GE Arize Life

The primary application of the GE Arize Life LED light fixture is as a replacement for fluorescent lights typically found in tissue culture labs, growth chambers and testing labs. The fixture is available as a 2-, 4- and 8-foot light bar.

“This fixture has an integrated power supply, is IP66 rated and UL wet rated, which means it’s splash proof and easy to clean,” Thornton said. “If the fixture is used in a high moisture environment, it is easy to wipe clean. The operating temperature can be from 0ºC-40ºC (32ºF-104ºF). The fixtures can be daisy-chained from end to end or they can be daisy-chained with a jumper cable.”

Thornton said the Life fixture, which has a 5-year limited warranty, previously had a L80 of 36,000 hours. She stated GE has updated the fixture to a L90 of 36,000 hours.

“This means at 36,000 hours a grower will still have 90 percent of the fixture light intensity available,” she said. “Other fixtures on the market are at L70 at 35,000 or 25,000 hours. That means at either 35,000 or 25,000 hours a grower is going to get 70 percent of the light intensity. A grower would have to replace the fixture if he loses 25-30 percent of the light intensity. Within that time period at 90 percent a grower may not have to replace the GE light fixture depending on what he is growing.”

Thornton said replacement of the fixtures will depend on where they are used.

“If the fixtures are used in a vertical farm where they account for 100 percent of the supplemental light the plants are receiving, those are usually operated 16-18 hours per day,” she said. “The lights won’t be operating 24 hours because the plants have to have some time to rest. At a rate of 16 hours of light, seven days a week, the fixtures would run approximately 5,000 hours per year. The life expectancy of the fixtures would be around seven years.

“This is what we typically see with some of our other applications. That is why we are able to offer a longer life expectancy. GE has been doing this with its other products. We know how to mechanically and electronically put the products together and run them at a higher efficiency in order to get a longer life. For growers who are using the lights for propagation rather than for a vertical farm, the life expectancy could be even longer if the lights aren’t run as often or as long.”


GE Arize Lynk

Side-by-side the Lynk and Life light bar fixtures look identical. The GE Arize Lynk fixture is available as a 4- and 8-foot light bar with plans to release a 2-foot bar in 2017.

“The biggest difference between the two fixtures is the light intensity,” Thornton said. “The Lynk fixture can be used with vertical farms, in greenhouses, and growth chambers. Like the Life fixture, Lynk is IP66 rated and UL wet rated so it can be cleaned very easily. The Lynk fixtures can also be daisy chained from end-to-end. It has an independent driver so there is no additional driver required. There is also a plug so that it can be hot wired or it can be plugged in.”

Thornton said because the Lynk and Life fixtures are lightweight, weighing less than 5 pounds, they are easy to install with mounting clips.

“The mounting clips are attached with fasteners and then the fixtures are attached to the clips,” she said. “It is a very easy and fast installation. Hort Americas has done a video showing how easy the fixtures are to install.”

Thornton said GE offers similar light spectrums for both the Lynk and Life fixtures.

“We have a reproductive spectrum, a vegetative and a balance. It depends on the goals of the growers,” she said. “The purple light is the ideal light for photosynthesis. Some growers want all purple and then they will move the crop out to harvest it. Others want white light so that they don’t have to move the product around. A grower can have a balanced pink, a balanced purple and a balanced white.

“The reproductive spectrum with a higher red content is for the grower who wants to promote flowering and fruiting. The light spectrum for vegetative growth, which has a higher blue content, is for the grower looking at size or selling the product by the pound. If a grower really doesn’t know what light spectrum he wants or wants a spectrum for both reproductive and vegetative, he can choose the balanced spectrum of red and blue. The balance is the more common spectrum chosen because growers want both or don’t know and want to see what happens with the balanced spectrum. If the balanced spectrum doesn’t produce a beefy enough plant then the grower will look at the vegetative spectrum. Or if the plant didn’t flower or fruit as well as expected, then the grower would use the reproductive spectrum.”

Thornton said the Lynk fixture puts out about twice as much light as the Life fixture.

“A 4-foot reproductive Life fixture produces about 43.2 micromoles per second (μmol/s),” she said. “A 4-foot Lynk fixture produces 82.9 μmol/s. So it’s almost double. There would be a similar difference for the 8-foot fixtures too. An 8-foot reproductive Life fixture produces about 86.3 μmol/s and an 8-foot Lynk fixture is around 181.5 μmol/s.

“We have seen a lot of the 8-foot fixtures used in vertical farms. Because of the insulation and they are so easy to clean, it is a lot easier to install the 8-foot fixtures. A lot of the vertical racks have five 8-foot sections so it works out perfect for the 8-foot light fixtures.”


GE Arize Greenhouse Pro LED Flowering Lamp

The GE Arize Greenhouse Pro LED Flowering Lamp is for photoperiodic control. It is set up on a BR30 platform.

“This bulb’s main application is to primarily control photoperiod and flowering in greenhouses,” Thornton said. “The light intensity of this bulb is 17.8 μmol/s. It is not as intense as the Arize light bar fixtures, but for its application it is very competitive with similar bulbs on the market. Its life expectancy is L90 at 10,000 hours. It is 90 percent at 10,000 hours.

“We have some trials going on at Michigan State University and expect to have some results coming out this year so that we can help growers use this bulb efficiently.”

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Grodan rockwool substrates offer growers more control

Grodan stone wool products offer the benefits of high irrigation efficiency, plant steerability and uniform crop development.

Grodan stone wool substrates are made from basalt rock that is processed at a very high temperature (over 2,900ºF). This hygienic, inert substrate offers vegetable and ornamental plant growers the opportunity to control growth from propagation to harvest.

“Grodan stone wool products are inert,” said Rens Muusers, Grodan Technical Sales Manager for the USA. “This means the grower has full control over what is happening in the substrate. Being inert, Grodan stone wool doesn’t bind nutrients and chemicals like other substrate types may do. Any fertilizers, pesticides or other chemicals, including growth regulators, that are applied to the stone wool are available to plants.

Linked to stone wool’s inert nature, Muusers stated growers have more opportunities to steer their crops.

“Other substrates that aren’t inert may bind elements, pesticides or other chemicals that are applied to enhance plant growth or health,” he said. “This may result in having to apply more of a chemical in order to have the same efficacy. The amount of chemical that will need to be applied to stone wool will be lower and it will be more effective than in non-inert substrates. This also helps growers to minimize their input costs.

“Using methods to control water content and EC (electrical conductivity) levels within the substrate allows growers to influence plant growth.”

Muusers stated by controlling the water content and EC in the stone wool, growers can influence the plant balance between vegetative and generative development.

“The steerability offered by Grodan products can result in earlier production, improved plant, fruit and flower quality and improved plant health,” he said. “All of these benefits result in better resilience to insect pests and disease pathogens.

“Also, stone wool can have a buffering impact on the pH in the nutrient solution, slightly increasing pH in the substrate. This increase is minimal compared to the impact of plant and microbial activity in the root zone on pH.”

Muusers indicated another benefit of using stone wool is crop uniformity.

“Because Grodan stone wool products are manufactured in state-of-the-art facilities with strict standards and quality controls, it is a very uniform substrate,” he said. “Depending on the Grodan product being used, this allows growers to produce very uniform crops. The uniformity of seedlings produced in stone wool plugs results in faster germination and quick crop establishment.


Grodan AO plugs and Grodan AX plugs

Grodan AO and AX stone wool plugs are ideal for starting many crops. The plugs are available in sheets that fit into 1020 trays. AO plugs are connected to each other at the top of the plugs. AX plugs are attached to each other at the bottom of the plugs. Muusers said there are also some options in regards to the seeding hole size as well as with the dimensions of the plugs.

“The properties of the AO plugs are exactly the same as the properties of the AX,” he said. “The only difference is where the plugs are attached to each other.

Grodan AX 25/40 cube with lettuce roots and stem post-harvest.

“AO plugs are ideal for NFT systems with smooth gutter surfaces and also for deep flow systems. Some NFT systems use gutters with grooves on the surface for which growers may prefer the wider base and greater bottom surface area of the AX plugs which may be more stable in these systems.”

Muusers said both plugs are used mainly for leafy greens and culinary herb production. There are also growers who are using them for aquatic plants.

Grodan Cress Plate

The Cress Plate is a fairly new product used primarily for the production of microgreens. It is the thinnest product of Grodan. It is only 1 cm thick, less than ½ inch.

Cress Plates come in two sizes. One size fits into 1020 trays. A larger size is used by some growers who need customized sizes. Growers are able to cut the Cress Plate sheet to the exact size they need.

“The Cress Plate has the same beneficial characteristics as other Grodan products,” Muusers said. “It’s inert, clean and hygienic. It’s a uniform product. It holds water evenly. The Cress Plate also provides quick, easy germination and even development of a microgreen crop.”

Muusers indicated growers use Cress Plates in a couple of ways.

“Some growers sell the microgreens with the Cress Plate, essentially selling a living product,” he said. “This allows the end consumer to use the freshest product longer, something that is valued by customers like restaurants. “Growers who produce baby greens and baby lettuce tend to harvest off of the Cress Plates. By harvesting higher up the plants, the plants continue to grow and produce for several harvests. This multiple harvest method is preferred to the uncommon practice of reusing substrates.”

Muusers stated reusing the Cress Plates is risky, just like reusing any substrate.

“There is the possibility of sterilizing the used substrate with steam or some other technique,” he said. “When a sterilizing technique like steam is used, it can have a negative impact on the properties of the substrate. I wouldn’t recommend harvesting and then resowing on top of a previously used Cress Plate because of the risk with potential disease issues and the potential negative impact on germination and growth.”

Grodan Delta Blocks

Grodan blocks come in different sizes and are ideal for both ornamental and vegetable crops.

“Depending on the crop, once a seedling is germinated in a plug it can be transferred into a block and then transplanted into a finish substrate to be grown on,” Muusers said. “Tomatoes and peppers are usually propagated in plugs and then transplanted into blocks. The final grower purchases the young plants in blocks and transplants them into the final substrate such as Grodan slabs. For cucumbers, which are a relatively quick crop, those are sometimes sown directly into blocks, instead of plugs.”

There are different size blocks for different size crops. A standard block size is 10 cm-by-10 cm-by-6.5 cm, which is referred to as a 4-inch block.

Muusers indicated that some growers put multiple plants into one block depending on the crop.

“For tomatoes, growers are looking for a certain head density per square meter,” he said. “The head density per square meter is sometimes achieved by growing multiple plants or by pinching the plants. Tomatoes are the primary crop that growers plant more than one seedling in a block.”

Muusers stated this method of planting multiple plants is also done with cucumbers and peppers. Another reason a grower sows multiple plants into blocks is to try to save on the cost of the blocks.“Some growers use 6-inch blocks instead of 4-inch blocks and put two plants in them,” he said. “In my opinion, it is always better to put one plant in one block. There is less competition resulting in better seedling uniformity as well as a more uniform crop.”

The blocks, like the plugs, are inert and are steerable. Muusers stated the blocks are also important in regards to irrigation efficiency—how the water content and more particularly, the EC, are refreshed within the substrate.

“Grodan focuses on good root growth and uniform root growth throughout the blocks,” he said. “Also, the blocks need to be able to withstand the rigors of handling during propagation. Their structure must remain stable throughout the growing process to be able to support the plants especially when the blocks are moved around. The blocks won’t break or fall apart.”


Grodan Gro-Slabs

Muusers indicated that Grodan slabs come in different product types developed to meet the challenges and needs of different crops.

“We have different slab types for different applications,” he said. “The slabs differ in fiber orientation and fiber thickness to deliver the kind of functionality a grower is looking for. The Grodan plugs and blocks have the same fiber orientation. They are designed for quick root establishment.”

There are Grodan slabs designed for vegetable crops. These crops are usually short term, less than one year. There are slabs designed for longer horticultural ornamental crops that are grown for longer than a year. The slabs for long term crops, including cut roses and gerbera, have a stronger fiber structure to withstand the longer production period.

“Grodan slabs are very uniform,” Muusers said. “Since the substrate is inert, they offer a high degree of crop steerability. This offers a lot of options for irrigation strategies combined with the substrate to influence plant development in a vegetative or generative way.”


David Kuack is a freelance technical writer in Fort Worth, Texas;


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Growers, researchers learning how, where and when to use supplemental lighting

Before growers invest in supplemental lighting they need to determine the impact of natural light levels on their crops.

One of the things that University of Florida horticulture professor Celina Gómez tries to reinforce with growers when talking about supplemental lighting is the importance of the daily light integral. Daily light integral is the sum of photosynthetic light (photosynthetically active radiation) received by plants in a day. Gómez did a presentation on “Yield Responses to Supplemental Lighting” at the Northeast Greenhouse Conference in November.

“Solar DLI will determine the light intensities that growers need and for how long they will need to run supplemental lights or even if they need supplemental light,” Gómez said. “Growers should be aware of the DLI whether they are growing greenhouse vegetable or ornamental crops. It is one of the most critical factors.

“Fruiting vegetable crops have a fairly high DLI requirement, usually between 20-25 moles of light per square meter per day (mol·m-2·d-1). For most ornamental crops, the DLI won’t likely be more than 12 moles since growers are not trying to develop fruit.”

Celina Gómez, environmental horticulture professor at University of Florida, said knowing the solar DLI will determine a grower’s need for supplemental lighting.
Photos courtesy of Celina Gómez, Univ. of Fla.

Gómez said growers may find it difficult to determine the optimal DLI for various crops.

“This information isn’t the easiest to find and there can be differences between similar species,” she said. “Finding the optimal DLI can be especially difficult to find for uncommon horticultural crops. During my presentation I had one greenhouse grower ask me about the optimal DLI for potato seed production.”

While knowing a plant’s DLI is important, Gómez said it is just as important for growers to know how much light is being delivered by the sun.

“Knowing what a crop is getting from the sun will determine how much a grower is going to need supplemental light or if he even needs supplemental light,” she said. “A grower may benefit from supplemental light for only a few months or for most of the entire year depending on the crop and its DLI.”

More accurate light measurement

Gómez said one area where growers are making progress is how they are measuring light intensity.

“After so many years of talking about the best way to measure light that is useful to plants, growers are realizing how to more accurately measure light,” she said. “They realize the importance of monitoring the light intensity that their plants receive from sunlight.

“I expect that more growers have invested in quantum sensors to measure light intensity and if they are still using light meters they realize they have to be able to figure out how to convert those readings that makes sense in regards to plant growth. The growers are getting it and making the conversions from footcandles to other metrics like moles.”

Still learning about LEDs

Even though growers better understand the importance of DLI, Gómez said growers can still be overwhelmed by the choice of supplemental lights available, including high pressure sodium (HPS) and light emitting diodes (LEDs).

“Most growers don’t know exactly what specific wavelengths or spectrum or what light recipe are best for their crops,” she said. “In the case of LEDs, most growers are choosing white LEDs or a combination of colors like red and blue. When I started my PhD in 2011, most available LED arrays came in combinations of red and blue. More LED light manufacturers are adding wavelengths to their range, but most commercial LED units come with fixed wavelengths.

“Most growers don’t know which specific wavelengths work best for their crops. They are relying on what they are told by the LED manufacturers. If the growers know what they want to do with a crop, then the university researchers working with the LED manufacturers could be able to advise growers on what LED lights they should be using. It’s also going to be cheaper for the light companies to manufacture fixtures with a standard recipe than to try to come up with a specific recipe for every grower.”

Gómez said LEDs have been more widely adapted by controlled environment agriculture growers operating vertical farms and warehouse facilities.

LEDs have been widely adapted by controlled environment agriculture growers operating vertical farms and warehouse facilities.
Photo courtesy of Farmbox Greens

“While an increasing number of greenhouse growers are interested in LEDs, more of these growers are still using high pressure sodium lamps,” she said. “I generally don’t recommend that greenhouse growers switch from HPS to LEDs just yet. There is more information that needs to be determined for LEDs. HPS is the more established technology and greenhouse growers know what they are getting with these lamps in regards to light intensity, light quality and lifespan. When it comes to greenhouse applications, LEDs can still be considered a high risk technology for growers. Most greenhouse growers are still waiting to make the transition from HPS to LEDs.”

Additional LED research

Gómez said many of the research papers published about LEDs have focused on the effect of light quality or spectrum on several different crops.
“A lot of the plant responses are also affected and dependent on the intensity of light or light quantity– high light vs. low light,” she said. “Under different light intensities plants are going to have different responses. There is also the potential for differences in cultivar responses. Most growers are not going to use a specific red, blue, far-red, white, whatever ratio of light quality for one particular cultivar when they have hundreds of different cultivars in their production facilities.”

Another area Gómez said still has to be determined is the lifetime of the LEDs used in production greenhouses.

“This has to do with the greenhouse production environment where there can be high temperatures, high humidity and chemical application residues,” she said. “The life expectancy of a LED installed in a greenhouse in Alaska is not likely to be the same as the life expectancy in a greenhouse in Indiana due to the different environmental conditions within the greenhouses.”

Another area that Gómez said could use more research is the area of LED interlighting or intracanopy lighting.

“This is something that we were interested in when I was a student at Purdue University,” she said. “This use of LEDs even has potential applications in areas that have high light levels.

“There can be a lot of shading within the plant canopies of high wire crops like tomatoes, cucumbers and peppers, even if the light levels overhead are high. Research still needs to be done with intracanopy lighting and with the light quality of intracanopy lighting. The light quality for this intracanopy lighting may need to be different than the light quality for overhead lighting.”

Gómez said the use of intracanopy lighting could potentially provide light to those leaves that are shaded by the upper canopy or by neighboring plants.

Intracanopy or interlighting LEDs could potentially be used to increase fruit number, fruit size and fruit quality of high wire crops like tomato.

“Those leaves may be receiving low levels of light and not photosynthesizing so they are not contributing to the photosynthetic production of the plant,” she said. “There is the potential of using intracanopy lighting to increase the photosynthetic activity. We don’t know yet if that is true or if that is even going to make a difference in terms of production.

“We don’t know if the plants have already reached their maximum genetic potential. We may find out that there is increased photosynthetic activity with intracanopy lighting. The increase in overall production could include number of fruit and size of fruit. Another benefit is that a specific light wavelength could increase fruit quality. That could potentially be done with intracanopy lighting by placing the fixture close to the fruit clusters. In the case of tomatoes the levels of beneficial compounds like lycopene might be able to be increased.”


For more: Celina Gómez, University of Florida, Department of Environmental Horticulture, Gainesville, FL 32611-0670; (352) 273-4568;;

David Kuack is a freelance technical writer in Fort Worth, Texas;

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Substrate trials look to assist hydroponic growers avoid propagation-related issues

Substrate trials in Hort Americas’ research greenhouse are looking at conventional and organic propagation substrates along with different irrigation strategies for producing healthy starter plugs for hydroponic production systems.

Hort Americas has retrofitted a 12,000-square-foot greenhouse in Dallas, Texas, for the purpose of studying edible crop production in a variety of hydroponic production systems. The greenhouse is also being used to demonstrate products offered in the company’s online catalog.

Tyler Baras, who is the company’s special projects manager, is overseeing the trialing of conventional and organic substrates in different production systems.

Tyler Baras, special projects manager at Hort Americas, is overseeing the trialing of leafy greens and herbs propagated in conventional and organic substrates. The seedlings are transplanted into a deep water culture, NFT or vertical tower production system.
Photos courtesy of Tyler Baras, Hort Americas

“The trials I am focusing on are organic substrates vs. conventional substrates,” Baras said. “I’m primarily using stonewool or rockwool as the conventional propagation substrate. I am also starting to trial some loose substrates, including peat and perlite.

“The seedlings are never moved into another substrate. The seed is sown into plugs and then the rooted seedlings are moved into a deep water culture, NFT (nutrient film technique), or vertical tower production system. The plugs are really only useful for the first two weeks in propagation. Then it is really about getting the roots to grow outside the plugs so the roots grow directly in the water.”

For the organic production systems, Baras is working primarily with expandable coco plugs. He has also started working with some organic loose substrates including coco peat and perlite.

For the substrate studies Baras is working with two standard hydroponic crops, basil and lettuce, primarily butterhead lettuce.

“When I’m testing the lettuce I use either raw or pelleted seed,” he said. “With basil it’s all raw seed. Basil tends to germinate relatively easily, whether the seed is planted into a dibbled hole or sown on top of the substrate.”

Focused on irrigation strategies

A primary objective of the substrate trials is to determine the best irrigation strategies for both organic and conventional substrates.

“This is probably more important with some of the organic substrates than the conventional substrates because the organic substrates tend to hold more water,” Baras said. “One of the big challenges that organic hydroponic growers run into is overwatering their plugs because coco holds more water than conventional substrate plugs that growers are used to. Coco plugs hold more water than stonewool, phenolic foam and polymer-based peat plugs. These other plugs dry out faster than coco plugs.”

For the substrate trials, rooted seedling plugs are finished in a deep water culture, NFT (nutrient film technique) or vertical tower production system.

Baras said growers who are moving from conventional to organic production tend to use the same irrigation techniques they employed with their conventional propagation program.
“The growers will continue to irrigate the plugs a couple times per day,” he said. “With a lot of the organic plugs, when the seed is sown, they only need to be irrigated once every three days. If the plugs are overirrigated the roots don’t have an incentive to search out the water when they are planted into the production system. The search for water is what drives the seedling roots down to the bottom and out of the plugs.

“The goal of planting into plugs is to have the seedling roots grow outside of the plugs into the water of the deep water culture or NFT system. If the plugs are overwatered as young seedlings, the roots don’t make it down to the bottom of the plugs so it takes longer to start the seedlings and sometimes they just end up rotting because the plugs remain too wet.”

Type of irrigation system

In addition to looking at the irrigation frequency of plugs during propagation, Baras is studying the impact of different methods of irrigation during propagation, including overhead and subirrigation.

“When deciding whether to use overhead or subirrigation, it depends on whether raw or pelleted seed is being sown,” he said. “If pelleted seed is going to be used, a lot of times it’s advantageous to use overhead irrigation because it helps to dissolve the coating surrounding the seed. This helps to ensure the seed has better contact with the substrate. Sometimes it’s almost a little easier to get good germination with subirrigation if raw seed is used because of the direct contact with the substrate.

Growers need to avoid overwatering young seedling plugs or their roots may not make it down to the bottom of the plugs, which could delay transplanting into the production system.

“Smaller indoor growers often use subirrigation for germination. A lot of the large growers, especially those coming from the ornamental plant side such as bedding plants, usually have overhead irrigation systems installed. These growers have propagation areas set up with overhead irrigation, which can be used to start their hydroponic vegetable crops.”

Baras said most indoor warehouse growers are not going to be using watering wands or overhead irrigation in their operations.

“Most of the warehouse growers will be using subirrigation, such as flood tables,” he said. “For them it is going to be important that they select the right kind of seed to get good germination. They may have to try other techniques like using a deeper dibble or covering the seed with some kind of loose organic substrate such as perlite or vermiculite. Growers using overhead irrigation can usually sow pelleted seed without having to dibble the substrate.

“Many growers tend to have issues when they are using pelleted bibb lettuce seed with subirrigation. We are looking at ways of increasing the germination rate using dibbling with the pelleted seed or increasing the dibble size or covering the seed.”

Baras said growers who are using automation, including mechanized seeders and dibblers, prefer to use pelleted seed.

“With pelleted seed it’s easier to be more precise so that there is only one seed planted per plug cell,” he said. “I have seen automation used with raw basil seed. I have also seen organic production done where automation was used just to dibble the plug trays. Dibbling seems to be one of the biggest factors when it comes to getting good even germination.


Need for good seed-substrate contact

Baras said occasionally with tightly packed coco plugs, if the seed is not pushed down into the plug the emerging radicle may have issues penetrating the substrate.

“This helps push the radicle down so it contacts the substrate and establishes more easily,” he said. “When subirrigation is used it can be advantageous to cover the seed with vermiculite or just brush the top of the coco plug after the seed is planted to get some coverage of the seed.

“What usually affects the way that coco plugs work is the size of the coco particles. There is really fine coco. There is coco fiber, which can be mixed into the plug to help with aeration and increase drainage. We are looking at various plugs with some increased fiber content trying to aerate the plugs in order to speed up the drainage.”

Stonewool or rockwool is the primary conventional propagation substrate in the trials. Other loose substrates, including peat and perlite, are also starting to be trialed.

Baras is also looking at using loose substrates in different ratios in plugs and then transplanting them into deep water culture, NFT, and vertical tower systems.

“One of the issues with hydroponic systems and loose substrates is these substrates can enter the production system and clog up the irrigation lines,” he said. “The trick is trying to avoid having any loose substrate enter the system. We are looking at using loose substrates and allowing the seedlings to establish longer in the plug cell during propagation before transplanting them into the production system. This enables the seedlings to develop a larger root system, which can prevent loose substrate from falling into the system.”


For more: Hort Americas, (469) 532-2383;

David Kuack is a freelance technical writer in Fort Worth, Texas;


Products being used in greenhouse trials

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NG2.0 from GRODAN: The New Standard for Optimal Irrigation

Grodan NG2.0

Press Release

Precision Growing has never been so Precise

Next Generation 2.0 (NG2.0) is the latest substrate technology from GRODAN. This technology enables propagators and growers to produce more while using less water, nutrients and space. It creates optimal growing conditions for a whole season, and allows roots to make better use of the entire substrate. NG2.0 is available in plugs, blocks and slabs to help growers and propagators produce sustainable, healthy fresh produce for a growing population.

The growing world population means the demand for sustainably produced and healthy fresh produce is continuing to increase. The greatest challenge facing growers is creating the ideal conditions for growth: not just for a few weeks, but all year round. Precision Growing plays a vital role in this respect. It gives growers the opportunity to produce more using less water and nutrients.

The next step in Precision Growing

GRODAN introduced Next Generation Technology in 2007. Its introduction already signaled a giant leap forwards in crop management, plant steering and root development. NG2.0 is an exciting continuation of this technology that has been extensively trialed in practical situations over the past years. The response to NG2.0 is extremely positive. NG2.0 is the next step in Precision Growing (see video below).

NG2.0 adds new benefits to those already offered by Next Generation Technology. Water distribution is even more uniform and even better utilization of the entire substrate volume by the crop is ensured.

Continual new growth of roots in both the block and the slab results in a healthier and more vigorous crop throughout the whole growing season. These benefits translate to higher yields, improved fruit quality and reduce the sensitivity of the crop to diseases. NG2.0 creates the perfect substrate for growers and propagators of plants.

Phased transition to NG2.0 in North America

Beginning in 2016, GRODAN will implement NG2.0 starting in the Netherlands in a phased in approach.

Future launches of NG2.0 will occur in other markets in Europe and North America. For more information on your specific area, please contact GRODAN (see below).


About the GRODAN Group

The GRODAN Group supplies innovative, sustainable stone wool substrate solutions for the professional horticultural sector based on Precision Growing principles. These solutions are used in the cultivation of vegetables and flowers, such as tomatoes, cucumbers, sweet peppers, eggplants, roses and gerberas.

The Group offers stone wool substrates together with tailor-made advice and tools to support Precision Growing, facilitating the sustainable production of healthy, safe, and tasty fresh produce for consumers.

Sustainability plays a prominent role at GRODAN, from the production of stone wool substrates to end-of-life solutions.

Founded in 1969, the GRODAN Group is active in more than sixty countries worldwide. The Group’s head office is in Roermond, the Netherlands.


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Fertilizer trials look at leafy greens, herb growth in hydroponic production systems

Early results from fertilizer trials in Hort Americas’ research greenhouse show knowing the levels of nutrients in fertilizer solutions can go a long way in avoiding problems with deficiencies and toxicities.

Hort Americas has retrofitted a 12,000-square-foot greenhouse in Dallas, Texas, for the purpose of studying edible crop production in a variety of hydroponic production systems. The greenhouse is also being used to demonstrate products offered in the company’s online catalog.

Tyler Baras, who is the company’s special projects manager, is overseeing the trialing of leafy greens and herbs in five different production systems.

“We’ve got a deep water culture or raft system using Hort Americas’ fertilizer blend with calcium nitrate and magnesium sulfate,” Baras said. “We are using that same nutrient mix in a nutrient film technique (NFT) system and a capillary mat system.

“I’m using Terra Genesis organic fertilizer in a vertical grow tower. I’m also using the same organic fertilizer for all of the seedling propagation in a flood-and-drain vertical rack.”

Tyler Baras, special projects manager at Hort Americas, is overseeing the trialing of leafy greens and herbs in different production systems, including deep water culture and nutrient film technique. Photos courtesy of Tyler Baras, Hort Americas
Tyler Baras, special projects manager at Hort Americas, is overseeing the trialing of leafy greens and herbs in different production systems, including deep water culture and nutrient film technique.
Photos courtesy of Tyler Baras, Hort Americas

Baras said the fertilizer recipe he is using in the deep water culture and NFT systems is based on general recommendations from Cornell University and the University of Arizona for leafy greens crop production.

Differences in nutrient levels

The deep water culture system has been running for three months. The water reservoir for the system is 8,000 gallons.

“Even if water evaporates, since it is such a large body of water, the electrical conductivity (EC) doesn’t really move much,” Baras said. “The EC has been very stable during the three months it has been operating. The reading has barely moved.”

The first trial with the NFT system, which has a reservoir of about 140 gallons, lasted for three months.

“Every week I added an additional 40 gallons of water on average to the NFT reservoir,” Baras said. “The water is evaporating and the salts are accumulating a lot faster in the NFT reservoir than in the deep water culture system. Because the NFT system has a smaller water reservoir, the quicker evaporation rate and the water replacement in the reservoir, has caused the EC to shift a lot more.”

One of the goals of the fertilizer trials is to see what salts are accumulating in the NFT system and to see how long the system can run before it has to be flushed.
One of the goals of the fertilizer trials is to see what salts are accumulating in the NFT system and to see how long the system can run before it has to be flushed.

Baras said even with the changes in nutrient levels all of the plants have been performing well.

“I haven’t seen any nutrient deficiencies or toxicities even as the fertilizer recipe has shifted over time. We have been trialing a wide range of crops, including butterhead and romaine lettuces, kale, spring mixes and basil. I’m trialing a lot of crops to figure out when these crops start to be impacted by possibly too much salt accumulation. I haven’t seen anything yet that is alarming.

“One of the things that I have seen over the years working with fertilizers is how wide the acceptable range is for plants to grow well. Between the NFT and deep water culture, the NFT is using half the nitrogen and the plants are performing very similarly. There are recommendations for EC, but none of these fertilizer levels are set. I have some systems that have 20 parts per million phosphorus and some that have 50 ppm and the plants look the same. Most general recommendations say 40-50 ppm. I’ll have some solutions that have 3 ppm iron and others that have 6 ppm iron. It is interesting to see how wide the range is for a lot of these nutrients and the crops are performing the same.”

During the three months that the deep water culture system has been running the electrical conductivity (EC) has been very stable with plants showing no signs of nutrient deficiencies or toxicities.
During the three months that the deep water culture system has been running the electrical conductivity (EC) has been very stable with plants showing no signs of nutrient deficiencies or toxicities.

Baras said he has seen a slowing of plant growth in the NFT system.

“I’m not seeing any deficiencies or toxicities, but the crops have slowed down about a week over the deep water culture,” he said. “Depending on the crop, it’s taking a week longer to reach either the plants’ salable weight or height.

“The slowing in growth could be related to the nutrients. This could be useful information for growers. If they are checking the EC, which may have been 2.3 when a crop was started, if there is a slowing of growth, growers may want to have a water test done. The test could show that the amount of nutrients might be changing.”

Identifying what makes up the EC

During the three months that Baras had been running the NFT system he never flushed the system.

“All that I’ve done with the NFT system is add water and additional fertilizer to maintain a targeted EC,” he said. “One of the goals of the trials is to see what ions are accumulating in the system and to see how long I can run the system before it has to be flushed. When I started the target EC was 2.2-2.3. I still achieved the target EC at three months, but the composition of what was actually in the water changed.

“Originally the NFT fertilizer solution contained about 185 parts per million nitrogen. At the end of the trial the EC was the same but there was only 108 ppm nitrogen in the solution. The calcium concentration was originally 250 ppm and ended at 338 ppm. Sulphur was originally at 80 ppm and rose to 250 ppm. Nutrients have accumulated as the water evaporated. Solely going by the EC meter reading doesn’t tell the full story of what is in that water. The EC of the fertilizer solution that I started with is the same as the EC for the fertilizer solution three months later. The difference is the ions that are making up that ending EC.”

Herb production with organic fertilizer

Baras is growing a variety of cut herbs in vertical grow towers. The plants are fertilized with Terra Genesis, a molasses-based organic fertilizer. He said Hort Americas has been hearing from tower growers who are interested in trying to grow organically.

“What we are seeing is the organic fertilizer solution can change a lot over time,” he said. “The fertilizer tank solution matures as time goes on. With the organic fertilizer, the nutrients tend to balance out as the solution is run longer.

“Our city water contains calcium and some magnesium. These elements are actually the nutrients that the organic fertilizer is slightly low in. So as I run the system longer, through the addition of city water, I actually start to see an accumulation of both calcium and magnesium, which actually helps balance out the total fertilizer recipe. The balance of the nutrients has improved over time.

A variety of cut herbs are being grown in vertical grow towers and fertilized with Terra Genesis, a molasses-based organic fertilizer.
A variety of cut herbs are being grown in vertical grow towers and fertilized with Terra Genesis, a molasses-based organic fertilizer.

The pH was fairly unstable as it seemed to be going through several biological waves. It was moving rapidly between high and low. As I run the tank solution longer the total alkalinity has increased, which has stabilized it. The biological activity has also started to stabilize. The pH has stabilized in the upper 5 range. For the plants grown organically I have seen deficiencies pop up. The deficiencies were reduced as the fertilizer tank solution ran longer. The deficiencies appear to have balanced out.”

Baras said one noticeable difference between the NFT, deep water and vertical grow towers is how much slower the plants grow in the towers.

“I don’t know what to contribute the slower growth to yet,” he said. “It could be trying to determine the best fertilizer rate for the fertilizer. It could be the crop selection, because most of the crops in the towers are different from what I’m growing in the NFT and deep water culture.

“I’m going to start a deep water culture and NFT trial using organic fertilizer. I’ll have three different organic production systems running simultaneously so I will be able to compare the plant growth in each system. I’ll also be able to compare the growth of the same crops grown with organic or conventional fertilizers.”

Controlling biofilm, disease pathogens

Baras said one of the issues that can arise with using organic fertilizer is the development of biofilm in the irrigation lines that can cause emitters to clog.

“I am incorporating a product called TerraBella, which contains beneficial microbes,” he said. “These microbes help mobilize certain nutrients, like phosphorus, which can promote the formation of biofilms. This biofilm buildup is usually more of a problem with high water temperatures.

“About every six weeks I add a booster application of the beneficial microbes depending on the production system. The deep water culture system has a larger reservoir so I am not replacing evaporated water as often. For the other productions systems, like the NFT and grow towers, where I am replacing the water, I am incorporating the beneficials more often. For these systems, the fresh city water that is added dilutes the fertilizer solution. Also, there is chlorine in the city water that possibly could negatively impact some of the beneficial microbes.

For more: Hort Americas, (469) 532-2383;

David Kuack is a freelance technical writer in Fort Worth, Texas;


Products being used in greenhouse trials



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Hort Americas retrofits greenhouse for trialing hydroponic growing systems, products

Hort Americas’ special projects manager Tyler Baras is using a 12,000-square-foot hydroponic greenhouse to teach company staff and customers what it takes to economically grow leafy greens and herbs.

Tyler Baras is a well-traveled grower. He has worked in Florida and Colorado growing hydroponic greenhouse vegetables, including organic crops. He is now taking the knowledge and experience he has gained from those growing operations and putting it to use in a 12,000-square-foot demonstration and research greenhouse in Dallas, Texas.

Baras, who is the special projects manager at Hort Americas, is overseeing the trialing of leafy greens and herbs in five different production systems along with the testing of potential products for the company’s online catalog.

“Chris Higgins, the general manager at Hort Americas, brought me to the greenhouse and asked if I would be interested in running a demonstration and research facility,” Baras said. “He was also interested in collecting data and writing a book about leafy greens production.

“After I agreed to accept the position, I drew up blueprints of the greenhouse, preparing a design of the production systems, writing a budget and proposals on how it was going to look, and how much it was going to cost to operate, including projected sales from the produce that was grown.”

Tyler Baras, special projects manager at Hort Americas, is overseeing the trialing of leafy greens and herbs in five different production systems. Photos courtesy of Tyler Baras, Hort Americas
Tyler Baras, special projects manager at Hort Americas, is overseeing the trialing of leafy greens and herbs in five different hydroponic production systems.
Photos courtesy of Tyler Baras, Hort Americas

The retrofitted greenhouse is located behind a grocery store and prominent Dallas garden center. The grocery store and garden center will allow Baras to test his projected budgets and produce sales.

“The greenhouse was originally built for growing bedding and flowering plants,” Baras said. “It was built with passive ventilation and was not designed for leafy greens production. We had to make some major modifications. Renovations included leveling the floor, adding a vestibule air lock, upgrading the electrical system, installing evaporative cooling pads, insect screening and landscape fabric, and upgrading the motors for the shade system along with installing new shade cloth. We have been growing in the greenhouse since September.”

Hort Americas, which is a horticulture and agriculture wholesale supply company, provided the materials for the retrofit along with the hydroponic production systems that Baras will be using. The production systems include a capillary mat system, a deep water culture floating raft system, a nutrient film technique (NFT) system, a hydroponic tower system and grow racks. Hort Americas has also provided a variety of equipment and products, including substrates, fertilizers, LED lights and other products it offers to its wholesale customers.

Collecting, disseminating production data

Dallas was chosen for the research location because it is one of the hardest places to grow hydroponic leafy greens. Baras will be trialing primarily leafy greens, including a variety of lettuces (bibb and Romaine), kale, bok choy, basil and other herbs.

“We believe that if leafy greens can be grown here then they can be grown nearly anywhere by everyone,” he said. “Year-round production here is difficult. We know that we will be able to grow during the fall, winter and spring. The tricky part is going to come during the summer when there are high temperatures and high humidity. The project will take a minimum of a year to collect the data.”

Baras said he will be collecting a lot of data including: cost per plant size, how much does it cost over the production cycle to operate each system and the labor costs involved with operating each system.

The 12,000-square-foot demonstration and research greenhouse contains five different production systems including a deep water culture floating raft system.
The 12,000-square-foot demonstration and research greenhouse contains five different production systems including a deep water culture floating raft system.

“The goal is to collect data that can be used by everyone,” he said. “We are going to collect data that includes the total light delivered. If growers in more northern latitudes are dealing with lower light, they can look at the light levels we maintained in the greenhouse and reach those same levels using supplemental light so that they can mimic the exact same conditions.

“The data collected will be available to whoever has an interest in reading about it. This will enable growers to be knowledgeable about making decisions about these production systems and operating them. They will also have access to some real world baseline data from trials so they will know if they are achieving the proper metrics. For example, we will share the data of how long it took to grow a certain size head of lettuce or a certain weight of basil using specific inputs. Growers will be able to look at real world environmental conditions under which a crop was grown.”

Preliminary results

Baras said based on initial production results what makes most financial sense at this time is growing basil and lettuce.

“Our initial metrics from the data that we have collected have been good,” he said. “We are producing 8- to10-ounce heads of bibb lettuce in 38 days and we are harvesting commercial size sleeved basil in 26 days from seed.

“Most commercial standards for lettuce in the U.S. are between 6 and 10 ounces. For basil there is a wide range in regards to the standard size for weight. Generally it is done by size or by what fills up a 10-inch tall sleeve. We have been able to fill a 10-inch sleeve and make it look really good.”

Preliminary production results include harvesting commercial size sleeved basil in 26 days from seed.
Preliminary production results include harvesting commercial size sleeved basil in 26 days from seed.

Having experienced a warmer than normal October, Baras said the water temperature in most of the production systems has been 85ºF or warmer.

“Generally the water temperature for most hydroponic crops is between 65ºF-70ºF,” he said. “The water temperature here is definitely warm, but we are still having really great growth. So far it is looking like we can grow a crop during the summer. But we haven’t gone through a full summer yet and that is going to be the real test.
Baras said they want to try to avoid chilling the water and will only use this production technique as the last resort.”

“We are trying to find ways around having to chill the water, including increasing the level of dissolved oxygen in the water using a variety of methods. This includes using Venturi aerators, and if needed, injecting liquid oxygen. These methods are less costly than running chillers. Chillers can be expensive and they use a lot of energy.
“We really want to find a model that is going to be acceptable to small scale growers. We are trying to keep the inputs to a minimum and still achieve our production goals.”

Teaching and trialing

Baras said the greenhouse has already been used for onsite training.

“That is one of our main goals with the site,” he said. “We want to be able to bring in people and provide them with hands-on training, both our customers and the Hort Americas staff. For example, we want to be able to show them how to blend fertilizer, what the process looks like for moving seedlings through a hydroponic system, how to measure light levels in a greenhouse and best pest control methods.

“We want to be able to assist customers who are starting to build a greenhouse and are looking to install hydroponic equipment. The greenhouse will enable them to see what is involved before they make any purchases.”

Dallas Grown
The greenhouse will be used to provide training to Hort Americas’ customers and staff, as well as the trialing of new products.

The greenhouse will also be used for trialing new products.

“Companies often approach Hort Americas about carrying their products, the greenhouse will enable us to put them through real world trials before they’re put in our online catalog,” Baras said. “Some of the products we plan to trial include dosing systems, monitoring systems for greenhouse environmental control and meters for measuring pH and EC. We are open to looking at other equipment and other automation technology.”

For more: Hort Americas, (469) 532-2383;

David Kuack is a freelance technical writer in Fort Worth, Texas;


Products being used in greenhouse trials

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LEDs offer option for photoperiodic control

Research at Michigan State University shows growers have a choice when it comes to lights for photoperiodic control.

As light bulb manufacturers phase out the production of incandescent bulbs, growers are looking for replacements to control flowering of ornamental plants. Researchers at Michigan State University have compared the efficiency and efficacy of LEDs for flowering applications with traditional light sources including incandescent, fluorescent and high-pressure sodium lamps.

“After we determined that LEDs were as effective at controlling flowering as other traditional light sources, we began to look more closely at how different wavebands emitted by LEDs actually regulate different aspects of flowering and photomorphogenesis,” said Michigan State Ph.D. graduate research assistant Qingwu (William) Meng. “In our experiments we used experimental LEDs manufactured by a company in Japan called CCS and commercial LEDs from Philips Lighting. For this particular study we used four different LEDs that are commercially available to growers to control flowering.”


Qingwu (William) Meng is studying how different wavebands emitted by LEDs actually regulate different aspects of flowering and photomorphogenesis.
Photos courtesy of William Meng, Mich. St. Univ.


Meng used an Apogee spectroradiometer to collect data from the four different LEDs.

“We measured the spectral output from 350 nanometers to 850 nanometers,” Meng said. “We were able to measure the total light intensity from each of the four lamps to quantify the exact spectral distribution.”


Lamp placement impacts light intensity

Meng said he did not compare the light output data he collected with data reported by the light manufacturers.

“It is relatively difficult to find light intensity data from some of the light manufacturers,” he said. “What some companies report in regards to light output is the total photon flux from the light source captured by an integrating sphere device that we don’t have here at Michigan State. Others show a graph of the emission spectrum, but the spectral data are not available.

“For greenhouse flowering applications the lamps can be installed at different heights. Depending on the distance between the bottom of the light source and the plant canopy, there can be different levels of light intensity. Even though a light may be advertised to have a very high light output, if the lamps are hung high above the plant surface then growers are going to get a lower light intensity at the plant level. It is very situational and depends on how far apart the lights are spaced out in the greenhouse and how high the lights are installed above the plant canopy.”


Ensuring proper light spacing

Meng said growers typically space out LED lights for flowering regulation about 10 feet apart horizontally.

“Light uniformity and light intensity are the two most important characteristics,” Meng said. “To ensure that there is an accurate layout of the lights, it is ideal to conduct a trial to see exactly what is happening below the lights. Growers can go into a greenhouse at night and measure the light intensity under the lights to see if the light intensity is sufficient and the light distribution is uniform. Light uniformity is very crucial. A grower doesn’t want to cause non-uniform flowering of the same crop.

“Growers can take one light and then measure the light output at different points under the light. By measuring the light distribution, growers can determine where the highest output and lowest output occur under the lamp. If growers don’t have the expertise to develop a light map, they can consult lighting experts.”

Some lighting companies have developed software to design light maps.


Differences in wavelength effects

Meng said for effective photoperiodic control only 1-2 micromoles per square meter per second (µmoles/m2/s) at plant height is needed either to promote flowering of long-day plants or inhibit flowering of short-day plants.


If red or far red are the predominant wavebands provided by LED lamps, 1-2 micromoles per square meter per second should be effective for speeding up the flowering of long-day crops.
If red or far red are the predominant wavebands provided by LED lamps, 1-2 micromoles per square meter per second should be effective for speeding up the flowering of long-day crops.


“For specific wavebands, red light is the most prominent in terms of regulating the flowering pathways of plants,” he said. “The four LEDs lamps we tested that are all marketed for flowering applications, all have some level of red or red/far-red light. If red or far red are the predominant wavebands, then 1-2 µmoles/m2/s should be effective for most flowering crops.

“In contrast, if only blue light, which is from 400-500 nanometers, is used to regulate flowering, there won’t be any effect if a low intensity of 1-2 µmoles/m2/s is provided. Blue light at 1-2 µmoles/m2/s doesn’t create long days for a variety of photoperiodic crops. However, when the intensity of blue light is elevated to 15 or 30 µmoles/m2/s, blue light is able to regulate flowering as effectively as red or as a red/far red combination. Overall, the efficacy of a lamp depends on its light spectrum.”


Differences in plant species sensitivity

Meng said for different ornamental species or cultivars there are different sensitivity levels in terms of the light spectrum that should be used to control photoperiod. He trialed about 20 different photoperiodic ornamental crops popular with commercial growers.

“For long-day plants, including petunia and pansy, there should be red light or a combination of red and far-red light to speed up flowering,” he said. “Some crops, like snapdragons, are really sensitive to far-red light. In this case, growers should use lamps that emit both red and far-red light to accelerate flowering, otherwise flowering won’t be promoted at all.”

He said for petunias, plants flower earlier under red light, but with both red and far-red light, flowering can be promoted even more.

“In order to achieve the benefits of photoperiodic lighting to promote flowering of long-day plants, growers should look at the crops they’re producing, and then decide what kind of spectrum the LEDs should have to provide the maximum capability of flowering promotion,” Meng said.

For more: Qingwu (William) Meng, Department of Horticulture, Michigan State University, East Lansing, MI 48824;
Meng is working with professor Erik Runkle;;


Funding for this research was provided by USDA National Institute of Food and Agriculture’s Specialty Crop Research Initiative, Michigan State University’s Project GREEEN, and horticulture companies supporting Michigan State University floriculture research. Nate DuRussel, Michigan State University greenhouse research technician, provided greenhouse technical assistance, and C. Raker & Sons and Syngenta Flowers donated plant material.


David Kuack is a freelance technical writer in Fort Worth, Texas;





New horticultural lighting blog

LightHort is a science blog created by Qingwu (William) Meng to communicate the latest scientific findings on light in horticulture to the public. Meng is working with graduate students from various institutions, including Michigan State University and Purdue University, specializing in photobiology and horticultural lighting to employ various forms of multimedia to effectively deliver scientific ideas worth sharing. A variety of topics are covered ranging from sole-source lighting for plant factories to photoperiodic and supplemental lighting for greenhouse operations. Follow LightHort on its website, Facebook and Twitter.

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Expanding Possibilities with e-GRO®

Smart app signals new era in Precision Growing for GRODAN customers

ROERMOND, the Netherlands, − GRODAN, a global leader in stone wool substrate solutions introduces e-Gro: an easy to use, mobile app that gives real-time substrate information. e-Gro is a new service from GRODAN developed to support customers with a GroSens® MultiSensor system. Customers who need to have real-time reporting on their substrate, now have the opportunity to link their GroSens system to the e-Gro app. This new mobile and desktop application provides growers the possibility to get the maximum out of their substrate. It’s easy to use and very accurate. e-Gro is the perfect platform for professional growers interested in expanding their possibilities and keeping control of their growing in real-time. Making Precision Growing accessible from anywhere.


With the introduction of the GroSens MultiSensor system in 2013, GRODAN took the first step to enable Precision Growing by offering a tool that gave professional growers highly accurate and reliable insights into the root zone. “With technology continuously playing a more important role, we recognized the need to add a new, smart dimension to the system to service our customers 24/7 anywhere in the world regarding their irrigation strategy” explains Hub Janssen, Managing Director at GRODAN. “With e-Gro, root zone management is no longer a one-way-traffic activity, it becomes individual, easy to access and intelligent. And this is only the beginning, as we will continuously expand features and functionalities of the app over time. e-Gro is a great new service for our customers”.

What are the benefits of e-Gro?

  • e-Gro is mobile: easy to use at anytime and anywhere on your online smartphone, tablet or desktop
  • e-Gro is interactive: customise and optimise irrigation strategy with alerts and notifications year-round 24/7
  • e-Gro improves decision making to maximize production and fruit quality

e-Gro is available in combination with GRODAN slabs and the GroSens MultiSensor system. The app can be downloaded for free and is available in the Google Play (Android) and App Store (iOS) and can be accessed via smartphone, tablet or desktop. To find out more about e-Gro, visit


About the GRODAN Group

grodanThe GRODAN Group supplies innovative, sustainable stone wool substrate solutions for the professional horticultural sector based on Precision Growing principles. These solutions are used in the cultivation of vegetables and flowers, such as tomatoes, cucumbers, sweet peppers, aubergines, roses and gerberas. The Group offers stone wool substrates together with tailor-made advice and tools to support Precision Growing, facilitating the sustainable production of healthy, safe, and tasty fresh produce for consumers. Sustainability plays a prominent role at GRODAN, from the production of stone wool substrates to end-of-life solutions.

Founded in 1969, the GRODAN Group is active in more than sixty countries worldwide. The Group’s head office is in Roermond, the Netherlands.

For more information and images:

Stefanie Wienhoven, Corporate Communications Manager

Tel: + 31 (0) 475 – 353481

email: and

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Monitoring is crucial for growing lettuce and leafy greens year round

Since lettuce and leafy greens have short production cycles, greenhouse growers need to stay focused if they want to be successful growing these crops year round.

The increasing demand for locally-grown vegetables is causing more field vegetable growers, ornamental plant growers and new growers to look at trying to satisfy this market. Cornell University horticulture professor Neil Mattson said he works with all three types of growers.

“I see both vegetable field growers and ornamental greenhouse growers trying to produce lettuce and leafy greens year round,” he said. “Both are quite common. Field vegetable growers are looking for a crop that can generate year-round cash flow. Ornamental growers are looking to fill their greenhouses in the off-season. A lot of ornamental growers no longer produce poinsettias in the fall or spring bulb crops and spring plant propagation that they would normally do in the winter. Growers could have as much as a six-month window when their facilities are not being used.”

Mattson said ornamental growers tend to better understand what it takes to grow a year-round crop.

“Ornamental growers tend to be aware of differences in crops and the problems that can arise,” he said. “They also understand the concept that there is much less light in the winter so they may have to consider using supplemental light. Ornamental growers are usually aware of the high cost of heating a greenhouse year round, especially during the winter.

“In general, field vegetable growers who have greenhouses, may only be using those structures in the spring to produce their transplants. That means they may be used to heating a couple months each year.”


Controlling environmental parameters

During this year’s Cultivate’16 conference and trade show in Columbus, Ohio, Mattson did a presentation on the year-round production of leafy greens using controlled environment agriculture (CEA). The main environmental conditions growers need to monitor and control include light, temperature and relative humidity.



Mattson said in the northern half of the United States light availability during the winter months is the most difficult environmental issue to deal with when growing plants year round.

“The target light level for lettuce production is 17 moles of light per square meter per day (daily light integral, mol/m2/d) for optimal growth,” he said. “In most parts of the country achieving that target usually isn’t an issue during the summer. In the winter, in the northern part of the country, light levels can be 5 mol/m2/d on average and even 1-3 mol/m2/d is common. That is three to five times less light than what is needed for optimum lettuce growth during the winter.”


Photo 1, Lettuce overview 1, Neil Mattson, Cornell Univ.
The target light level for lettuce production is 17 moles of light per square meter per day (daily light integral) for optimal growth.
Photos courtesy of Neil Mattson, Cornell Univ.


Mattson said supplemental light, using LEDs or high pressure sodium lamps (See the Lamps Needed Calculator, can be provided to deliver higher light levels to increase lettuce biomass. But going above 17 mol/m2/d can cause growers to have issues with tip burn.

“In the case of head lettuce, a grower can go from seed to harvested head (5-6 ounces) in 35 days if there is 17 mol/m2/d. If there is only 8.5 mol/m2/d, it takes the plants twice as long to produce that same biomass.

“For baby leaf greens, if they are seeded and transplanted and grown on for two weeks before harvesting and only receive 8.5 moles of light, the plants will only produce half the yield. If a grower normally harvests 10 ounces per square foot and there is only half the light, the plants will produce only 5 ounces per square foot.”

Mattson said a rule of thumb for New York is a grower can light a 1-acre greenhouse and produce the same yields as not lighting a 3-acre greenhouse to produce the same yields during the winter months.



Lettuce and many other leafy greens are cold tolerant. Mattson said a lot of growers want to grow them cold.

“The Cornell CEA research group proposes that these crops be grown at fairly warm temperatures so that they have the faster 35-day crop cycle,” he said. “This is based on having 17 mol/m2/d and a daily average temperature of 70ºF-75ºF during the day and 65ºF at night.

“During the winter the issue with temperature is paying to heat the greenhouse. It’s easy to control the temperature, growers just have to be willing to crank up the thermostat.”

Mattson said temperature can be really hard to control in southern climates in the U.S.

“Under hot conditions, temperatures in the 80s and 90s, head lettuce is going to bolt prematurely,” he said. “It can be difficult to drop the day temperature low enough to avoid early bolting.”

Beyond trying to reduce the air temperature, research done by the Cornell CEA group has shown that lowering the root zone temperature to 74ºF or less using chilled water can help prevent premature bolting.

“Chilling the root zone temperature allows growers to grow using warmer air temperatures by having the cooler water temperature,” Mattson said. “This is an effective way to chill the plants even when the air temperatures reach the 80s and 90s.”

Mattson said the biggest issue with warmer air temperatures occurs with lettuce and spinach. Warmer temperature and long day conditions can both cause spinach to experience premature bolting. Mattson said warmer temperatures can also promote Pythium root rot on spinach. Spinach is much more susceptible to this water mold than lettuce or other leafy greens.

“Chilling the root zone temperature can help to prevent the disease organism from developing as quickly as at warmer temperatures,” Mattson said. “If the root zone temperature can be kept cool, it won’t completely avoid the Pythium issue, but it will help control it.”


Pythium baby leaf spinach, Neil Mattson, Cornell Univ.
Cooling the root zone temperature won’t completely avoid Pythium disease, but it will help control it.


Pythium spinach closeup, Neil Mattson, Cornell Univ.
Close-up view showing Pythium root rot on spinach.


The Cornell CEA group found that the optimum root zone temperature for spinach was 64ºF-65ºF. At this temperature Pythium was deterred, but there was no crop delay. If the root zone temperature is lowered to 62ºF, plant growth is slowed.


Relative humidity

Mattson said the relative humidity for lettuce and leafy greens should be between 50-70 percent. He said the lower humidity helps to limit pathogen issues.

“High humidity favors powdery mildew and Botrytis,” he said. “High humidity also favors the physiological disorder tip burn. Tip burn is caused by a calcium deficiency. The higher the relative humidity the less transpiration occurs in the plant resulting in the plant not taking up an adequate amount of calcium.”


Lettuce tipburn, Neil Mattson, Cornell Univ.
High humidity favors the physiological disorder tip burn, which is caused by a calcium deficiency.


Mattson said a relative humidity lower than 50 percent can cause an outer leaf edge burn, which is a physiological disorder.

“This is a different disorder than tip burn caused by calcium deficiency,” Mattson said. “The outer leaves develop lesions where the veins end on the edge of the leaves. The lesions occur where the sap exudes out of the veins and then is reabsorbed by the plant and there is a kind of salt buildup.”


Fertilization, water quality

Although fertilization and water quality are not environmental parameters, growers can have issues with both if they don’t monitor them. Lettuce and leafy greens are not particularly heavy feeders compared to other greenhouse vegetables like tomatoes and other vine crops. Mattson said lettuce and leafy greens are relatively forgiving crops when it comes to fertilization.

“Growers need to monitor the nutrient solution every day in regards to pH and electrical conductivity (EC),” he said. “The reason for testing the nutrient solution at least daily is because in hydroponics the nutrient solution pH can change by one or two units in a day.”

Mattson said for container crops like petunia and geranium, pH does not usually change by more than one unit in a week. He said container growers may check the pH every week, and some may only do it every two weeks. But for hydroponics a grower needs to stay on top of changes in pH.

In addition to daily pH and EC monitoring, Mattson said a detailed elemental analysis of the nutrient solution is important.

“Periodically, about every four weeks, growers should send a sample of their nutrient solution to a testing lab to determine if the plants are absorbing nutrients in the proportions the growers expect,” he said. “Certain elements in the solution may decline over time and a grower may have to add more of these elements and less of others.”

Mattson said some systems, like CropKing’s Fertroller, have automated sensors which measure pH and EC in line so it’s a real time measurement. The controller makes the necessary adjustments.

“Typically if a grower is putting high alkalinity water into the system, the pH tends to creep up over time, so the controller automatically adds acid to reach a target pH,” he said. “Likewise, the machine does that with EC too. If the EC is going down because the plants are taking up nutrients, the controller adds fertilizer stock solution to reach a target EC.”

Mattson said iron deficiency due to high pH is the most common nutrient disorder he sees on lettuce and leafy greens. Occasionally magnesium deficiency occurs because the water source contains enough calcium, but not enough magnesium.


Iron deficiency due to high pH is usually the most common nutrient disorder on lettuce and leafy greens.


“Many fertilizers don’t include calcium and magnesium, so growers can run into issues with magnesium deficiency,” he said. “Basil tends to have a high need for magnesium. We usually recommend basil be provided twice as much magnesium as lettuce.”


Photo 6, Basil magnesium deficiency, Neil Mattson, Cornell Univ.
Basil tends to have a high need for magnesium and usually should receive twice as much magnesium as lettuce.


Mattson said growers should test their water more frequently to determine if there have been any changes in the alkalinity of the water, including calcium, magnesium and sodium concentrations.

“In the Northeast this summer, we are experiencing a drought,” he said. “I’ve heard from growers who say the EC of their water is going up, which implies that some salt levels are going up. But we don’t know specifically which salts and that would be useful to know what specifically is changing.

“It really depends on their water quality. In particular, EC, alkalinity and whether there are any nutrients in high concentrations, like sodium, can be an issue. It really comes down to how long they are trying to capture and reuse the water. In our Cornell system we have traditionally grown in floating ponds. We use that same water cycle after cycle for several years. We can continually use the same water because we start with deionized water. However, even if the water has fairly low salt levels, using the same water will result in the accumulation of sodium to harmful levels over time.”


For more:
Neil Mattson, Cornell University
School of Integrative Plant Science, Horticulture Section
49D Plant Science
Ithaca, NY 14853
(607) 255-0621

Cornell Controlled Environment Agriculture “Hydroponic Lettuce Handbook”


David Kuack is a freelance technical writer in Fort Worth, Texas;


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Green Sense Radio invites Chris Higgins to look at the Latest in Green Agriculture


Growing Green with Chris Higgins of Urban Ag News, Singularity University, HP’s Deforestation Goals

Aug. 7, 2016  Chris Higgins of Urban Ag News and Hort Americas joins us for our feature, a look at the latest in green agriculture, Growing Green. He’ll tell us about the new Agrihood trend.

Singularity University is a benefit corporation that helps people,  businesses, institutions, investors, NGOs and governments understand cutting-edge technologies, and how to use them to positively impact billions of people. Nicholas Haan is Director of Global Grand Challenges and Team Project Leader at Singularity University.

The year 2020 could be a big one for HP, maker of printers, PCs, mobile devices and other technologies. It recently made the pledge to achieve zero deforestation by that year. To explain more is Judy Glazer, global head of product sustainability with HP.

About Green Sense Radio:

Founding Farmer Robert Colangelo is also founder and host of the nationally syndicated Green Sense Radio show. Recorded live on the Farm, Green Sense Radio features entrepreneurs, innovators, academics, and policy makers who are making the world a better place.

The program is heard coast to coast every week. Send us an email if you’re interested in sponsorship opportunities so your sustainable message can reach our millions of listeners!

Click here to listen to the latest Green Sense Program and subscribe to our weekly podcast.

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Hort Americas is an innovative leader in North America’s controlled environment agriculture industry (CEA) and strives to continually innovate in agriculture via premium technical support, professional salesmanship, unmatched customer service and outstanding products to our customers in the United States, Canada, Mexico, and the Caribbean.

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Taking LEDs to the next level

McGill University bioresource engineer Mark Lefsrud said it’s time to take plant research and production to a higher level with LEDs.

Much of the research that has been done with LEDs for the last 50 years has been conducted with low light levels.
“The biggest research area right now is with LEDs at high intensities of light,” said Mark Lefsrud, associate professor in the Bioresource Engineering Department at McGill University in Quebec, Canada. “We have to get into high intensity lighting studies to truly understand what is happening in plants. NASA has done some preliminary work with high intensity LEDs, but we have taken the research further.”

Mark Lefsrud, McGill University
Mark Lefsrud at McGill University is starting to do high intensity lighting studies to understand what is happening in plants under light levels of 5,000 micromoles and higher.
Photos courtesy of Mark Lefsrud, McGill Univ.

Lefsrud said most of the earlier LED studies that he and other researchers have been doing have looked at light levels of 150 micromoles of light (micromoles per square meter per second or μmol·m-2·s-1) and lower, and how the plants responded to those light levels.

“No one grows plants at 150 micromoles,” he said. “Plants are usually grown at 300 micromoles and higher. We have gone well above 1,500 micromoles and in some of our LED tests, we have gone as high as 5,000 micromoles. The plants start responding to what I consider to be more normal field type conditions.”


Incorrect assumptions

Lefsrud said the reactions of plants to higher light levels are not what the assumptions have been up to this point for all the earlier research.

“One assumption is that shade plants can’t handle light levels as high as sun plants, which is actually backwards,” he said. “We have found that it is the complete opposite. We are finding that shade plants are able to handle higher light intensities better than sun plants.

“Lettuce is considered a shade plant and tomato is considered a sun plant. When we shine 5,000 micromoles of light on these two plants, the tomato plant suffers and we can kill it quite easily. We don’t see the death of lettuce at higher light levels. Lettuce carries on like nothing has happened to it.”

Lefsrud said that one assumption is sun plants tend to be more succulent with thicker leaves so they can handle higher light levels.

“Another assumption is that shade plants, even though they’re called shade plants, aren’t true shade plants,” he said. “They’re sun spot plants. They can handle the bright light beams that come through the plant canopy and then the light beam disappears and they prepare for the next beam. The sun spot plants have more adaption for fluctuations in light levels as opposed to sun plants which have to receive more continuous high light.”


Higher light level LEDs

Lefsrud said it’s possible that growers haven’t tried producing at higher light levels because they were unaware that the plants can tolerate these levels.

“Another reason is that we have never been able to achieve higher light levels of 5,000 micromoles from these lamps,” he said. “And would it be cost effective to even try to produce these light levels? Now that we know that we can achieve higher light levels, let’s see what we can do with them. As research scientists we have to get up to higher light intensities. Currently we are trying to do things up around 10,000 micromoles of light.

“We’ve had to make the high light lamps ourselves or had them custom made to reach these light levels. That is one of the challenges—being able to manufacture lights that can reach these high light levels.”

Lefsrud said nearly half the energy that is going into an LED comes out as light, the other half is heat that has to be dealt with.

“The lights that give off these higher levels generate a lot more heat,” he said. “We have to use a water cooled jacket to cool the LEDs that produce 5,000 micromoles.

“Most LED bulbs can’t handle that kind of heat and burn out. When we started pushing these bulbs, the manufacturer told us the bulbs can’t handle the heat. We were told the bulbs would only last a few seconds at these high intensities. We cooled the bulbs down to -20ºC (-4ºF) with a water jacket and were able to run the bulbs for two weeks.”

Lefsrud said the technology is coming quickly and he expects that within the next year LEDs will be able to deliver these higher light levels.

“It’s not only the plant reactions at those light levels, but it also changes how the lights can be installed,” he said. “Growers won’t have to shine light only from above any more. The lights will also be able to shine from below or on the side. The lights could be mounted on booms and be moved. There are also more possibilities with interlighting.

“We have assumed that the lamps have to be shined from above like the sun. We have done many research tests that have shone the lights from below the plants and they do just as well as when the light is shined from above.”


Maximizing plant growth

Another part of Lefsrud’s LED research deals with maximizing growth with the minimum amount of light possible.

“What are the wavelengths (colors) of light that produce the most amount of plant growth with the least amount of light possible?” he said. “We chose to study lettuce, tomato and petunia looking at the PAR light spectrum that was available. We have been looking at other wavelengths where we see plants growing at twice the normal rate. We are finding that the plants grow faster as we get away from far red light and more into the red.

“We think that we can produce lettuce plants at twice the speed. For a lettuce crop that grows heads weighing 20 grams in the first two weeks, we can speed up the crop development to produce 40 gram heads in the same amount of time. We can theoretically double the growth rate. Lettuce seems to be a more aggressive crop than tomatoes. We are not sure about the growth rate for tomato and petunia as we haven’t completed the research.”

Mark Lefsrud, McGill University tomato
Mark Lefsrud found the best growth rate for tomato is around an 8:1 to 10:1 red to blue ratio, around 640 nanometers for the red and 440 nanometers for the blue.

Lefsrud said the research is narrowing in on a few wavelengths that most researchers haven’t been paying much attention to.

“From a growth standpoint, we don’t think far red is useful at all,” he said. “It’s red and a couple of other wavelengths.

“We found the best growth rate for tomato is around an 8:1 to 10:1 red to blue ratio. Roughly around 640 nanometers for the red and 440 for the blue. The more blue that was used, the more flowers and fruit were produced. High levels of red (19:1) was one of the ratios we trialed, where we saw more vegetative (leaf) growth occurred, but there wasn’t as much flowering and fruit.”

Lefsrud said his research has not gone as far as determining what levels of red and blue light should be given while the plants are vegetative or when they are start to flower.

“We are fairly sure that higher levels of red light increase the vegetative growth and then after that a grower would want to go to a higher level of blue light for tomato,” he said. “For tomato, 40 days after germination, the plants should be given more blue light. There are a number of research papers that have indicated that higher levels of blue light cause increased flowering. We believe that the blue light is critical.”


For more: Mark Lefsrud, McGill University, Bioresource Engineering Department, Ste.-Anne-de-Bellevue, QC, Canada; (514) 398-7967;;


David Kuack is a freelance technical writer in Fort Worth, Texas;