What is the impact of light on Cannabis production?

Light is one of the most important environmental factors when trying to grow high value hemp products.

By Karla Garcia

Hemp (or industrial hemp) is a strain of the Cannabis Sativa plant species grown specifically for industrial uses of its derived products (fiber, food, building materials, paper, jewelry, clothing, cordage, animal bedding, bio-fuels, etc.) Hemp by definition is a variety of Cannabis that does not produce high levels of CBD or THC. “Cannabis” (no need of capital C) is usually used when speaking about varieties of cannabis sativa or indica used for medicinal or recreational purposes (more THC and CBD production). For the purpose of this article we will use the correct wording “Cannabis” (with a capital C all the time and italics), as this refers to the genus we are speaking about (Including hemp and cannabis varieties.)

Cannabis is a crop that differs from other horticultural crops. This is primarily because its yield cannot be evaluated based solely on the weight or number of flowers or leaves. The chemical compounds produced by Cannabis are a very important product of this crop. In order to produce high value Cannabis it is necessary to understand how environmental factors can be manipulated to enhance final product quality.

Controlled environment production

Consistent yields and quality uniformity between production cycles are important to Cannabis growers. This has resulted in more Cannabis growers operating in controlled environment facilities. CEA production in which temperature, humidity, light intensity, light spectrum and carbon dioxide (CO2) levels can be controlled offers the ability to grow Cannabis year round. Under stable environmental conditions growers can produce up to six harvests per year. This makes indoor cropping 15-30 times more productive than outdoor cultivation (Magagnini et al., 2018).

Impact of light

There are several environmental factors that play key roles in controlling yield, flowering, sex of the plants, and cannabidiol (CBD) and tetrahydrocannabinol (THC) concentrations in Cannabis. These factors include photoperiod, light intensity and light quality.


Tournois (1912) was the first researcher to demonstrate that Cannabis flowering is hastened by short days and delayed under long days. Hall (2013) also concluded that environmental factors, including temperature and photoperiod, can influence Cannabis’ reproductive abilities. In many plants, flowering occurs when the meristematic tissue receives signals produced by changes in temperature and/or light duration and/or quality.

Under stable environmental conditions Cannabis growers can produce up to six harvests per year.Photos courtesy of Jeanine Davis, N.C. St. Univ.

Sexual expression in Cannabis is largely genetic (Flachowsky et al. 2001), but can be altered by environmental influences. Tournois was the first to report sexual reversal in the Cannabaceae family when he observed the effects of short photoperiods on Cannabis. Tournois reported a tendency toward maleness in Cannabis despite most dioecious plants showing a female tendency under similar light conditions.

Many factors contribute to the sexuality of flowering Cannabis plants. Under average conditions with a normal inductive photoperiod, Cannabis plants flower and produce approximately equal numbers of pure male and female plants with a few hermaphrodites (both sexes on the same plant).

Under conditions of extreme stress, such as nutrient excess or deficiency, mutilation and altered light cycles, Cannabis plant populations have been shown to depart greatly from the expected one-to-one male to female plant ratio (Clarke, 1999). Clarke (1999) also found that photoperiods of less than 14-16 hours can promote premature floral transition concluding Cannabis displays a quantitative short-day response.
There are three distinct phases in Cannabis cultivation: propagation, vegetative growth and flowering. Recent applications for research of production purposes recommends the use of long photoperiods (18 hours) for the propagation and vegetative phases and short photoperiods (12 hours) for the flowering phase when using artificial lighting (Magagnini et al., 2018).

Light intensity

Several studies with Cannabis have demonstrated that increasing the light intensity can have a positive effect on plant photosynthesis and/or growth (Chandra et al. 2008; Potter and Duncombe, 2012; Vanhove et al., 2011).

However, there is not always a correlation between a higher photosynthesis rate and more vegetative growth with higher flower yields. For example, Potter and Duncombe, (2012) using different light intensity treatments, concluded no significant difference in mass foliage or total THC levels within the foliage. However, the same researchers reported an increase in flower yield and THC present in flowers with increasing light intensity.

In addition, Vanhove et al (2011) demonstrated that a higher light intensity with a plant density of 16 plants per square meter can increase yield and THC concentration in comparison to lower light intensity levels. This research also showed that the use of the same high light intensity, but under a higher planting density (20 plants per square meter), can affect yield. Chandra et al., (2008) also reported greater net photosynthetic and transpiration rates when the light intensity increased.

Light quality

Plant growth, morphology and metabolism can be manipulated by changing light quality. For example, it is known that blue light decreases internode length making plants more compact (Dong et al., 2014). Also, several studies have demonstrated that far-red and green wavelengths induce stem and leaf elongation (Franklin et al., 2005).

The same responses have been confirmed in a high number of crops including Cannabis. Lalge et al. (2017) concluded that in general, red and blue light spectrums cause shorter internodes, smaller leaf area and more compact morphology compared to a white light source. In addition, Hawley et al. (2018), reported a significant increase in yield and concentration of total THC when using intra canopy red and blue lighting compared to the sunlight control treatment.

Studies have shown increasing the light intensity can have a positive effect on plant photosynthesis and/or growth of Cannabis.

Livadariu et al. (2018) tested the use of green or blue light in Cannabis production compared to sunlight. Results showed a significant increase in yield and THC content when using green light and an increase in polyphenols, flavonoids and protein under blue light treatments compared to the control sunlight treatment.

Lyndon et al. (1987) demonstrated that THC content of some Cannabis plants can be increased by irradiating them with UV-B light. Marti et al. (2014) also corroborated the same response in a more recent study. However no other Cannabis chemical compounds have been confirmed to increase under UV treatments.

Comparing LEDs and HPS lamps

For many years Cannabis production was done mainly with high pressure sodium (HPS) lamps. It is now possible to control and improve Cannabis quality using LED lamps. A recent study by Magagnini et al. (2018) compared the production of Cannabis using HPS lamps and two different LEDs lamps (LED lamp 1: 12 percent blue, 19 percent green, 61 percent red and 8 percent far-red. LED lamp 2: 1 percent UV light, 20 percent blue, 39 percent green, 35 percent red and 5 percent far-red). The same light intensity of 450 μmol m-2 s-1 was used under all treatments.

Study results showed HPS lamps produced taller and higher stem dry weight compared to LED treatments. However, HPS treatments resulted in a significant decline in THC concentration in flowers compared to both LED treatments. Under LED light treatments plants were shorter and compact, but showed higher CBD and THC content. This shows that the optimized light spectrum improves the value and quality of Cannabis.

Studies comparing the impact on Cannabis grown under LED or high pressure sodium (HPS) lights, found LED-treated plants were shorter and compact with higher CBD and THC content.

More research is required to fully understand Cannabis’ behavior under artificial lighting. However, enough research information is available to show LED lamps are the best light source to improve Cannabis production and quality.

Hort Americas has technical specialists in artificial LED lighting who can offer numerous options and the guidance to determine which lights are best for your CEA operation. Contact Hort Americas’ technical service staff for additional assistance.


Chandra, S., Lata, H., Khan, I.A. and Elsohly, M.A. 2008. Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO2 conditions. Physiol Mol Biol Plants. 14: 299–306.
Clarke, R. C. 1999. Botany of the genus Cannabis. In Advances in Hemp Research. d. P. Ranalli, 1–19. New York: Food Products Press.
Dong. C., Fu, Y., Liu, G., and Liu, H. 2014. Growth, photosynthetic characteristics, antioxidant capacity and biomass yield and quality of wheat (Triticum aestivum L.) exposed to LED light sources with different spectra combinations. J Agron Crop Sci. 200:219–230.
Flachowsky, H., E. Schumann, W. E. Weber, and A. Peil. 2001. Application of AFLP for the detection of sex-specific markers in hemp. Plant Breeding. 120(4): 305–309.
Franklin, K.A. and Whitelam, G.C. 2015. Phytochromes and shade-avoidance responses in plants. Ann Bot. 96:169–175.
Hall, J., Bhattarai, S.P., Midmore, D. J. 2013. Review of Flowering Control in Industrial Hemp. Journal of Natural Fibers. 9(1): 23-36.
Hawley, D., Graham, T., Stasiak, M. and Dixon, M. 2018. Improving Cannabis Bud Quality and Yield with Subcanopy Lighting. HortScience. 53 (11): 1593-1599.
Lalge, A., Cerny, P., Trojan, V., and Vyhnanek, T. 2017. The effects of red, blue and white light on the growth and development of Cannabis sativa L. Mendel Net. 8 (9): 646– 651.
Livadariu,O., Raiciu, D., Maximilian, C and Capitanu, E. 2018. Studies regarding treatments of LED-s emitted light on sprouting hemp (Cannabis sativa L.). Romanian Biotechnological Letters. X:X.
Lyndon, J., Teramura, A. H. and Coffman, B. 1987. UV‐B radiation effects on photosynthesis, growth and cannabinoid production of two Cannabis sativa chemotypes. Photochemestry and Photobiology. 46 (2): 201- 206.
Magagnini, G., Grassi, G., Kotiranta, S. 2018. The Effect of Light Spectrum on the Morphology and Cannabinoid Content of Cannabis sativa L. Medical Cannabis and Cannabinoids. 1:19-27.
Marti, G., Schnee, S., Andrey, Y., Simoes-Pires, C., Carrupt, P.A., Wolfender, J.L. and Gindro, K. 2014. Study of leaf metabolome modifications induced by UV-C radiations in representative Vitis, Cissus and Cannabis species by LC-MS based metabolomics and antioxidant assays. Molecules. 19:14004–14021
Potter, D.J., Duncombe, P. 2011. The Effect of Electrical Lighting Power and Irradiance on Indoor-Grown Cannabis Potency and Yield. Journal of Forensic Sciences. 57: 618-622.
Tournois J. 1912. Influence de la lumiere sur la floraison du houblon Japonais et du chanvre. C. R. Acad. Sci. Paris 155: 297-300.
Vanhove, W., Van Damme, P. and Meert, N. 2011. Factors determining yield and quality of illicit indoor cannabis (Cannabis spp.) production. Forensic Science International. 212: 158-153.

Hort Americas to showcase products from key suppliers at Cultivate’19

If you’re heading to Cultivate’19 in July stop by the Hort Americas’ trade show booth to see the latest products for controlled environment agriculture and horticulture production.

Horticultural distributor Hort Americas is participating in this year’s Cutlivate’19 trade show, July 13-16, in Columbus, Ohio. Last year Hort Americas moved its booth (Booth No. 3317) to a larger location on the trade show floor. This larger booth enables Hort Americas to show more of the products it offers to controlled environment growers.
Attendees will have an opportunity to see a wide variety of production-related products, including LED lights, environmental sensors, greenhouse shading compounds, a variety of conventional organic and hydroponic fertilizers and growing substrates. Stop by the Hort Americas booth at Cultivate’19 and let its team members talk with you about its hydroponic and conventional growing products for edible crops, hemp and ornamental plants.

Suppliers talk about what’s new for 2019

Hort Americas sat down with representatives of some of its key suppliers to talk about what has them excited about their company’s product offerings along with what is happening in the controlled environment agriculture industry.

Current, powered by GE

Bruno D’Amico, Design and Product Manager

1. What’s new with Current, powered by GE’s lighting product line for 2019?

We are super excited to release more members of the Arize Element Top Light family, including the industry’s first one-for-one LED replacement for 1,000-watt high pressure sodium (HPS) products. The Arize Element is the most advanced greenhouse grow light on the market, enabling growers to grow more while consuming less power.
With efficacy levels up to 3.5 µmol/J, the Element is also the most efficient grow light on the market. The Element features a unique design that minimizes shadowing in the greenhouse, allowing more natural sunlight to penetrate. With multiple mounting features, including universal options, it also provides growers flexibility in installation.

2. What crops are these products applicable for?

Our products cater to a wide range of crops, including hydroponic lettuce and herbs, hemp and ornamental plants. What’s unique about our approach is that we combine our unmatched experience in lighting with the application knowledge of our trusted partner Hort Americas to design light recipes that maximize results, setting growers up for success no matter what they’re growing.

3. How are these products different from your competitors?

Our products are designed with purpose. We are very close with growers and listen to their feedback, allowing us to build products with the features that they value the most.

For example, we took our first Element top light and designed the second generation with their feedback in mind. We included multiple spectrums tailored to their growing needs. We completely redesigned our installation method to easily install on existing structures, which means growers can spend less time installing and more time growing. We also offer a five-year warranty as standard, for their complete peace of mind.

When growers choose our products, they are choosing products designed exactly for their needs.

4. What most excites you about 2019?

Connecting growers with new technology and learning from them. Technology in the horticultural lighting space is developing at a rapid pace, allowing growers to achieve greater outcomes than ever before by increasing crop yields, productivity and quality, all while reducing their operating costs. We’re excited to introduce growers to our complete portfolio of solutions that enable efficient growth at an industrial scale, and we look forward to their feedback. They are the key to our success.


Antony Yousefian, Director

1. What’s new with 30MHz’s product line for 2019?

There has been a wide range of functionalities added to our data-platform that are cracking the traditional barriers. An example of this is proximity to knowledge. People have to travel far to get advice or travel to see their crop. All this contributes to the slow feedback loop and analog nature.

30MHz feels that information is not a monopoly but a sharable good. That’s why we believe one of our most important updates is the implementation of a data feed and social features such as @mentions and the ability to upload images to that feed.

You can compare this with the way social media let people interact with each other, only in this case the subject of converse is crop data. It enables growers to explore information in a completely new way.

For example, they are able to invite crop consultants or IPM- or light-experts within their data environment and have them take a look at VPD, temperature, CO2 and PAR values. Another illustration of the social aspect of the platform is that growers with multi-location facilities, whether they are in the same country or not, are able to consult each other in a blink of an eye.

Another important aspect we’ve added is the capability to ingest climate computer data breaking down a common data silo, adding instant value in terms of time and energy-savings.

Jonathan Zwinkels, owner of Madestein, UK, has a clear view on this.

“Our experience of the ZENSIE/Priva integration was that it was fairly low effort on our part,” Zwinkels said. “We didn’t have to do a huge amount. It was quick, efficient and remote. We’ve seen a variety of benefits from bringing these data sources together.

“We’re able to cross-reference data. An example is VPD of basil leaf or stress points on lettuce. We’re able to graph the VPD data we get through ZENSIE and understand it in the context of climate control or ventilation positions. We can dig into the relationships between them, see the effects, and understand what needs to be changed to achieve our desired outcomes.”

2. What crops are these products applicable for?

Our data-platform is applicable to any kind of crop, including greenhouse tomatoes, peppers and cucumbers, hydroponic lettuce and herbs, strawberries, hemp and ornamental plants, or cultivation process. That’s because we do not provide consultancy, but facilitate the sector in every way we can.

3. How are these products different from your competitors?

We don’t see ourselves as competitors to any platform that is directly connected to a company’s own consultancy services. Our data-platform ZENSIE is not better because it’s faster, cheaper, equipped with more functionalities, etc. It’s better because it’s different. By different, we mean independent, transparent, value adding and community connecting. We’re here to help the sector digitize, to create more value with the same amount or even fewer resources.

4. What most excites you about 2019?

From a 30MHz point of view, we’re really happy with our recent series A funding. 30MHz has received an investment of 3.5 million EUR. The amount is used to accelerate product development and to further improve worldwide distribution. It’s our aim to create a space where all products and services are digitally accessible for growers, advisers, suppliers, distributors and researchers.

From a market perspective, we see a clear transition happening within the sector. There’s a tentative development going on in which growers, consultants, distributors and researchers are acknowledging digitization of processes more and more. Being able to grow more with less inevitably will require the assistance of digital aids.


Chooi Yiang Keh, National Sales Manager – Professional and Industrial Applications

1. What’s new with OSRAM’s product line for 2019?

After extensive product field testing with selected partners (NASA and Michigan State University) we’re ready to present and make available to customers our new horticulture light solution: Phytofy RL. With this smart horticulture light system, we would like to allow worldwide growers to really play with light, creating the best light recipe (spectra, intensity and photoperiod) for their crops.

2. What crops is Phytofy RL applicable for?

The system has been designed to be as flexible as possible for the end users. The wide light spectrum from UV-A (385 nm) up to far red (730 nm), the six independently dimmable light channels and the possibility of grouping together more fixtures will permit the end user to experiment with several crops types. With our partners we extensively tested microgreens, leafy greens, ornamental flowers and tissue culture plants.

In addition, we know the importance of making a profit from the beginning of the investment on new light sources. Therefore to enable customers a jump start we provide after product registration, a set of five different light recipes (all tested in OSRAM’s Smart Farming laboratory) to start growing basil, red lettuce, snack tomatoes, etc. Our dedicated email address (horticulture@osram.com) is open to customers (and potential ones) for any questions of such regard.

3. How is Phytofy RL different from your competitors?

To reduce risks of product commoditization, we identified some unique selling points as key pillars during Phytofy RL’s development.

  • Ultra-wide light spectrum. The presence of an UV-A channel combined with multiple wavelengths combinations (blue, green, hyper red, far red and warm white) allows researchers and all Phytofy RL users, in general, to build dedicated and unique light recipes
  • Photosynthetic photon flux (PPF) and light intensity focus. Quality matters, but quantity even more. To enable researches on many kinds of crops as well as determining the most efficient and effective light recipes, the quantity and the disposition of the LEDs has been deeply investigated during the ideation phase to maximize the PPF metric without requiring active cooling and granting the most uniform possible light distribution.
  • Smart functions. Control and integration with other systems are crucial for a product like Phytofy RL. Designed-on-purpose control software, running on most common PC operating systems, provided with a unique irradiance map feature permits the end user to control the Phytofy RL LED light system without further interactions with the crops. Additionally, should customers need a deeper system integration with their control systems, like climatic control chambers, OSRAM can provide communication protocol specification
  • Flat design. Phytofy RL is optimized for rack systems and vertical farms without needing active cooling.

4. What most excites you about 2019?

OSRAM’s vision is to become a high-tech photon champion company. We strongly think that with Phytofy RL we will support this idea within the smart farming industry. Phytofy RL will create the new requirements baseline for growers when selecting light systems for crop research. Last, but not least, we are eager to see the first integrations between light fixture, crops sensors and control systems. There is definitely interesting times ahead of us.


Ruben Lensing, Area Export Manager

1. What’s new with Sudlac’s product line for 2019?

In the North American market we’ve introduce the F-series, self-removing paints that wear off gradually over time and do not need to be cleaned off at the end of the season. This range is designed to offer growers an effective, user-friendly solution. It also makes a huge difference in costs because you do not need a cleaning product.
We also have introduced a new line of protection paints for greenhouses. Applied on various elements of the greenhouse structure, these solutions make it possible to maintain and protect your greenhouses from premature wear and tear.

2. What crops are these products applicable for?

The F-series can be used for all kind of crops, including greenhouse tomatoes, cucumbers and peppers, hydroponic lettuce and herbs, ornamental plants and hemp.

3. How are these products different from your competitors?

Our F-series are liquid paints so this is different from our competition, which offer mostly self-removable products in powder form. The difference between a liquid and powder is that a liquid is easier to apply and you achieve a more homogeneous layer.

Each of the Eclipse F-series (F2/F4/F6) paints produces the same results in terms of the shading rate, but offers a different protection time. The higher the number following the F, the longer the protection will last.

4. What most excites you about 2019?

I see that Sudlac is growing as a brand in the United States. I worked with Chris Higgins and his team at Hort Americas for the last two years to improve the brand name Sudlac has in the United States. The result is that a lot of growers used our products and have switched to Sudlac.

If growers are interested in our F-series and our other products, they are welcome to visit our trade show Booth No. 3416 at Cultivate’19. I would be happy to explain Sudlac’s product range. Sudlac’s booth is next to Hort Americas’s booth No. 3317.

This article is property of Hort Americas and was written by David Kuack, a freelance technical writer in Fort Worth, TX.

Largest hemp research center in the U.S. to open at Oregon State University

Analytics firm Brightfield Group, which tracks the cannabis industry, expects the hemp-derived cannabidiol (CBD) market to grow from $618 million in 2018 to $22 billion by 2022. Because of the growing interest in hemp and its potential to become a major agricultural commodity, Oregon State University is creating the country’s largest research center devoted to the study of this crop.

Continue reading Largest hemp research center in the U.S. to open at Oregon State University

Considering mixing your own fertilizer solutions?

It’s not that hard to do once you understand some fertilizer basics.

By Deidre Hughes

Mixing your own fertilizer solutions might seem like a daunting task at first. But once you understand some fertilizer basics you’ll realize it’s not that hard to do. One of the biggest benefits of mixing your own fertilizer solutions is the amount of money you’ll save. Another benefit of mixing your own solutions from dry fertilizers is that it requires less storage space than pre-mixed fertilizers which are often in liquid form.

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Current, powered by GE Showcases Horticulture Leadership at GreenTech with Industry’s First One-For-One 1000W HPS Retrofit for Greenhouse Growers

  • Current’s A Race to the Top – Geographical Trends in Vertical Farming session brings industry leaders and experts together to address dynamic market developments
  • The new greenhouse grow light is the most energy efficient on the market
  • Universal installation options allow the light to be installed in dozens of different ways, drastically reducing installation time

Press Release – AMSTERDAM–Yesterday at GreenTech, Current, powered by GE announced the release of the Arize Element* Top Light, the industry’s first one-for-one LED replacement for 1000W High Pressure Sodium (HPS) products. The Arize Element is the most advanced grow light on the market, allowing growers to get the most out of their greenhouse, for less. Continue reading Current, powered by GE Showcases Horticulture Leadership at GreenTech with Industry’s First One-For-One 1000W HPS Retrofit for Greenhouse Growers

U.S. organic sales hit a record $52 billion in 2018

The Organic Trade Association reports that 2018 marked a record year for U.S. organic sales topping $50 billion for the first time. Total sales of organic products reached $52.5 billion, up 6.3 percent from 2017.

Both organic food and non-food products reached record sales highs. Organic food sales were $47.9 billion, an increase of 5.9 percent over 2017. Organic non-food product sales were $4.6 billion, an increase of 10.6 percent from 2017.

Sales of organic fruits and vegetables reached $17.4 billion in 2018, a 5.6 percent rate of growth over 2017. Fruits and vegetables now account for 36.3 percent of all organic food sales. Organic fruits and vegetable account for 14.6 percent of all the produce sold in the United States. Market share of organic fruits and vegetables has nearly doubled in the last 10 years.

Business Is Always Blooming at Fantasy Orchids, Thanks to LEDs from Current Powered by GE

This article was originally posted on currentbyge.com

Stan Gordon discovered the ultimate houseplant in 1986 when a friend gifted him a single orchid commemorating the birth of his daughter. Fast-forward 33 years, and Gordon finds himself surrounded by over 70,000 orchid plants in a 10,000-square-foot greenhouse in Louisville, Colorado. Business is always “blooming” at Fantasy Orchids with an ever-changing assortment of colorful, fragrant flowers, thanks in part to new LED lighting from Current, powered by GE, that makes growing season a year-round proposition.

Continue reading Business Is Always Blooming at Fantasy Orchids, Thanks to LEDs from Current Powered by GE

Cornell University computer program helps identify food-borne pathogens

Cornell University scientists have developed a computer program, Environmental Monitoring With an Agent-Based Model of listeria EnABLe, to simulate the most likely locations in processing facilities where the food-borne pathogen listeria monocytogenes might be found. Food-borne listeria infects about 1,600 people in the United States each year with about one in five of those infections ending in death.

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Hort Americas and VegBed Team Up to Offer New Microgreen Medium for Farms

Hort Americas partnering with VegBed to offer their sustainable bamboo fiber microgreen mats

Press Release – NEW YORK, NY [February 12, 2019] – Hort Americas, North America’s top commercial horticultural supplier, and VegBed, the leader of innovative hydroponic growing mediums have announced today an exciting new partnership to offer microgreen farms a sustainable medium to grow with.

Continue reading Hort Americas and VegBed Team Up to Offer New Microgreen Medium for Farms