How Does Light Intensity Affect Cannabis Yields?

Empirical research on cannabis cultivation is difficult to find. The federal restrictions on studying it have hindered scientific knowledge regarding everything from its growth to its effects. While testimonials and personal experience give us some basis for understanding the plant, scientific studies are needed. When it comes to the effects of different types of light and light intensity on cannabis-specific behavior, the need for research is no different.

Driven by a desire for that data, Fluence Bioengineering and OutCo have collaborated on a groundbreaking new study into how light intensities affect plant growth and development. The two companies set out to evaluate and determine the optimal light intensity for yield and secondary metabolite production, particularly total active cannabinoid concentrations. “Looking at how light intensity impacts plant growth and development and cannabinoid profiles is something that hasn’t really been explored with photobiology research. Especially regarding cannabis, there’s really not much published yet,” says Josh Gerovac, horticulture scientist at Fluence Bioengineering.

The Two Companies Behind the Research: Fluence Bioengineering and OutCo

Fluence is an Austin, Texas-based company that designs and manufactures LED lighting applications for commercial horticulture operations. They supply LED lighting solutions to many of the largest cannabis and produce growers in North America. Their lighting systems have created increased yields, better quality and decreased energy spend for many cultivators.

OutCo is Southern California company, which grows medicinal and recreational cannabis. They’re committed to research and science to develop strategies to ensure consistent, high-quality products. As Dr. Allison Justice, OutCo’s VP of Cultivation puts it,

“Research drives our cultivation strategies. We follow the leads of commercial horticulture; we take methods from there and we implement them in an indoor growing setting to grow cannabis.”

Together, Fluence and Outco created a protocol and conducted an experiment evaluating the effect of five light intensities (400, 600, 700, 800, and 1200 µmol/m2/s) on the Hazy OG strain to study the effects on the growing process and yields.

The Effects of Light Intensity on Weight and Cannabinoid Production

So, what did the research show? Both shoot fresh weight and trimmed flower weight increased linearly as light intensity was raised. Interestingly, both also showed the greatest jump in production between 400–600 µmol/m2/s, with fresh shoot weight increasing 26 percent and trimmed flower weight increasing 51 percent. The test also showed that these increases slowed between 800–1200 µmol/m2/s (5 percent and 9 percent respectively), suggesting that around 1200 µmol/m2/s, cannabis is nearing its light saturation point.

Fresh Shoot Weight

Trimmed Flower Weight

Cannabinoid concentrations also proved interesting. Rather than a linear increase, the research showed that light intensity has little effect on the total overall number of active cannabinoids in the strain. What is evident, however, is that the LED treatments averaged a 12 percent increase in cannabinoid concentration over HPS lights, indicating the spectral composition may impact concentrations.

Total Active Cannabinoid Concentrations

To sum up the results, Justice says “What this experiment shows is that by increasing PPFD, we’re able to also increase yield. When we deployed Fluence SPYDRx PLUS in the trial (the fixture used to deliver 800 PPFD), we saw a 13.5 percent increase in yield, while using 44 percent less energy than our double ended HPS fixtures. For us, that’s huge. This doesn’t even take into account the energy savings from a reduced HVAC load.”

Using Data to Help Industry Cultivators

Fluence and OutCo hope that the data provided in these trials will help cultivators determine the optimal lighting solution to maximize yields, increase potency, and improve cultivation methods, which will in turn increase revenue for businesses. “We wanted to run a trial that would not only expand the research on cannabis, but also benefit growers to make an educated decision regarding the technology and cultivation strategy they implement in their grow to positively impact their business operations,” says Gerovac. “There’s very little research being done currently, and not a lot was done in the past,” says Justice, “so it’s an exciting time for Outco to be able to lead the pack to be able to prove some of these things; to really put some data out there to share with other growers. Being able to run the LED intensity trial with Fluence was huge.”

While this trial yielded important information about how light interacts with cannabis, there’s still a need for more tests and data to find out more about how light affects every aspect of cultivation. Together, Fluence and OutCo are hoping to further our understanding by collaborating on research and development going forward.

After reviewing the data from the test, OutCo decided to change their cultivation strategy. According to Justice, “Nothing speaks louder than data from a properly designed and repeated experimental trial. When my CEO was able to look at our harvest data comparisons of LED lights versus HPS, our decision to upgrade our rooms was immediate.”

“Because of the great results that we got from Fluence lights, and the data we were able to collect, we now want to implement our whole facility in LEDs. More specifically we are implementing double stacked benches. We expect this to bring us 2.5 times the square footage. We want to grow high-quality products. And to do this, we need to have the latest research, the latest technology. The Outco and Fluence relationship will only grow from here. Outco as a company plans to expand their operation, and as we do that, the science has proven that we should take Fluence with us.”

Find out more details on this study here.

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