How Optimizing Light Intensity Can Help Achieve Maximum Yield

How Optimizing Light Intensity Can Help Achieve Maximum Yield

Understanding and reconsidering this lighting variable can help increase yield and maximize revenue per square foot.

Light is at the core of plant health and development, according to Fluence Bioengineering’s VP of Marketing Travis Williams, and understanding the nuances and intricacies of light intensity can help cultivators optimize plant growth and yield, thus maximizing revenue per square foot.

Lighting is the foundation of yield, Williams says, and light intensity is a variable that can directly impact plant growth and development.

“Yield is the accumulation of biomass, and the accumulation of biomass is driven by photosynthesis. The word photosynthesis itself starts with ‘photo,’ meaning photon for light,” Williams says. “Photosynthesis is obviously driven by light, and if you neglect optimizing light, you neglect optimizing yield.”

Light intensity is one of the most critical aspects of lighting, Williams says. It is measured in photosynthetic photon flux density (PPFD). Williams says as a general rule, the more light a cultivator provides to a crop within certain parameters and environmental factors, the more yield that cultivator will get.

“Cannabis is a weed,” Williams says. “And just like other weeds, it’s a high DLI [daily light integral] crop, meaning that it requires and it wants a lot of light. We actually don’t know what the threshold is for how much light we can subject cannabis to before it hits a light saturation point.”

Williams says Fluence is conducting experiments now to pinpoint what cannabis’s light saturation point might be.

If a cultivator does not know what light intensity his or her crops are receiving, he or she will not know how to optimize other environmental conditions to take advantage of light intensity.

“Photosynthesis, and thus plant growth and development, is driven by light but it is a result of a culmination of environmental factors,” he says. “Light is obviously one of the key variables, but so is CO2, humidity, water, the nutrients in your soil, leaf surface temperature, the air speed around your plant [and] the genetics of your crop.”

Measuring light intensity is crucial, Williams says, to allow cultivators to optimize other environmental parameters to achieve optimal yield. He adds that there are also dangers of using light intensity that is too low or too high.

“If your light intensity is too low, you’re going to have less than optimal yields,” he says. “And if your light intensity is too high, say your light intensity is at 1,000 PPFD, but your air temperature and leaf surface temperature are very low, or you’re not supplementing CO2, then you’re going to hit a light saturation point where you’re simply wasting energy and your crop won’t be able to use all of the light that you’re giving it.”

How Lighting Can Help Produce Consistency 

Measuring light intensity and keeping it consistent over time can also help cultivators deliver a consistent product, according to Fluence’s Chief Business Development Officer Jerry Kieran.

“Consistency of light intensity being delivered to the plant from an improved spectral composition [eases] the gardening challenge so [cultivators] can better define and dial in their standard operating protocols so that their consumer from cycle to cycle can expect a much more consistent product and a similar experience,” Kieran says.

When growing under HPS, cultivators typically notice a pronounced depreciation of light intensity from cycle to cycle when yields decrease, Kieran says, and this leads them to change their lamps every six to 10 months.

Williams says a quantum sensor, the light meter that determines light intensity, measures PPFD and shows cultivators exactly how much light intensity they are giving their crops at any given time—allowing them to better optimize both light intensity and the other environmental conditions that will ultimately help them achieve maximum yield, increased revenue per square foot and product consistency.

“That’s the tricky part about lighting,” Williams says. “PPFD doesn’t just change with lamp depreciation, but also the distance you mount the lighting fixture from the canopy.  If your light fixture is mounted 6 inches away from your canopy, your canopy will get one intensity. If your light fixture is mounted 4 feet away from your canopy, you’re going to get another intensity. Understanding your lighting fixture’s depreciation value and its recommended mounting height go a long way in optimizing a consistent growing environment.”

“The [Fluence SPYDRx PLUS] lights produce perfectly even growth throughout the grow room with better PAR penetration through the canopy, which works great with the screen-of-green growing technique with low, wide plants,” said Giono Barrett, co-founder of Rainforest Farms.

The takeaway? Lighting is a critical variable to the success of any consistent cultivation environment, and it’s also a very complex and nuanced variable. LED technology is rapidly changing indoor and greenhouse growing, so while there’s plenty of resources to help growers educate themselves on these nuances, companies like Fluence are ready to help.

Photos courtesy of Fluence Bioengineering