The Lighting Approaches to Maximize Profits (LAMP) project aims to determine how growers can maximize their return on investment when considering installing grow lights.
As light emitting diodes (LEDs) become more efficient and more affordable, an increasing number of greenhouse and plant factory growers will consider installing LED luminaires to light their crops. In the case of greenhouse growers, these luminaires would provide light to supplement natural sunlight. For plant factory growers, production depends entirely on the light provided by an artificial light source including LEDs, high pressure sodium or metal halide luminaires.
The use of supplemental light to control downy mildew on food and ornamental crops could be integrated into current disease management practices.
Downy mildew is a major disease on both ornamental and food crops. Whether these crops are grown outdoors or in a controlled environment, environmental conditions, generally cool to moderate temperatures and high humidity, are favorable to downy mildew development. Warm temperatures and high humidity are conducive to powdery mildew development.
The LED light recipes that NASA scientists are developing on Earth could eventually be used by astronauts in space and growers on the ground to optimize the production of food crops.
National Aeronautics and Space Administration (NASA) has been growing plants in space for research since the early 1980s. Within the last five years, NASA has been focusing on growing plants in space primarily for food production and as an astronaut life support system.
Incorporating air or oxygen into irrigation water using nanobubbles can improve crop yields and reduce susceptibility to disease pathogens.
What started out as a way of making wastewater treatment systems more efficient with oxygen enrichment has expanded to how nanobubble aeration technology can improve production of agricultural crops. Moleaer Inc. in Torrance, Calif., filed a patent on nanobubble aeration technology in 2016 with the intention of using it as a way to deliver gas in a number of different applications.
When choosing horticultural lighting, growers need to consider lighting efficiency and how the lighting will be used.
There is a big difference between lighting efficiency for horticulture and lighting efficiency for consumer use. The difference is in who is receiving the light.
Whether growers are producing vegetables, ornamentals or other hydroponic crops, Hort Americas is working to provide its customers with the products and knowledge they need to be successful.
When Hort Americas in Bedford, Texas, started operating as a wholesale horticulture distributor in March 2009, the company had no existing customer base.
Increasing the oxygen level in the root zone can ensure healthy root growth and can impact crop yields.
Low oxygen levels in the growing substrate can play havoc with the health of both vegetable and ornamental plants. Shalin Khosla, greenhouse vegetable specialist at Ontario Ministry of Agriculture, Food and Rural Affairs in Harrow, Ontario, said a substrate oxygen level below 5 parts per million can have a negative effect on plant growth.
Sudlac shading products give greenhouse growers of flowers and vegetables the ability to increase and extend production during periods of warm temperatures and high light levels.
High temperatures and high light levels, especially during the summer can have negative effects on ornamental and vegetable crops produced in protected structures, including greenhouses. An economical way for growers to reduce light and temperature levels is by applying shading products to greenhouse glazing materials.
Trials with organic and conventional fertilizers in hydroponic production systems are showing it’s possible to produce edible crops at much lower nutrient levels.
Controlled environment agriculture growers have been trying to fit a square peg into a round hole by growing field crops in indoor environments. This is changing as research tries to match plant genetics with the production environment.
Even though the Greenhouse Lighting and Systems Engineering (GLASE) consortium is New York-based, the research it is doing has the potential to impact controlled environment agriculture worldwide.
How quickly hydroponically-grown lettuce and leafy greens seedlings are transplanted and their exposure to LED light during propagation can impact crop production times.
Most growers using traditional hydroponic substrates transplant lettuce and leafy greens seedlings as soon as the roots reach the bottom of the plugs. This usually takes from seven to 10 days.
If you’re going to use a loose substrate in a hydroponic production system, you may have to change how you handle starter plants and the treatment of recycled water.
Many growers of ornamental plants including annuals and perennials traditionally use a peat-based substrate such as 70 percent peat, 30 percent perlite. The growers, who produce these crops in containers, will often use the same substrates if they expand their crop offerings to include hydroponically-grown edible crops, including lettuces and leafy greens.
Growers have affordable options for ensuring plants receive sufficient oxygen in hydroponic production systems to maximize growth and to reduce the chances of disease.
Researchers at Michigan State and Iowa State Universities are looking for feedback from hydroponic food growers to help them determine where research is needed to benefit the industry.
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.
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.
“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.”
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; dkuack@gmail.com.
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