What cannabis cultivators need to know about green light

What cannabis cultivators need to know about green light

It is commonly believed that green spectrum light isn’t used by plants for photosynthesis, so it isn’t considered important for cannabis cultivators. 

But that is an oversimplification of green light, in that it does play an important role in photosynthesis and overall plant architecture.

Green light is considered “safe” for plants. Cannabis cultivators don’t think it can hurt a plant but they don’t always understand how it can help. Others believe it might not be beneficial enough, so they don’t use green light at all. 

So, what is the truth? Does green light help cannabis plants? Does it hurt? Or is it neutral – no clear benefit or problem?

A study by Michigan State University in 2014 indicated that plants grown with 50% green and 50% red light were shorter than those grown under red light. But when blue light was added or taken away, growth patterns changed. 

And adding green light can be beneficial to those who work in a growing operation, like cannabis cultivators, because it reduces eye strain. Preventing eye strain is important, as it can help cultivators spot things like nutritional deficits, disease or pests. 

The study also showed that green light penetrates the canopy better than other colors on the spectrum – something that is critical in cannabis growing operations.

Plants use the whole spectrum of light – we know this. With hobbyist growers, they tend to not add or subtract light on the spectrum simply because they either aren’t invested – or experienced – enough to try minute changes.

Using light on opposite ends of the spectrum is also old-school thinking, and it dates back to when cultivators only had one type of light (that only offered red and blue wavelengths) to choose from. 

But with the influx of cannabis cultivators adopting LED lighting technology, there is growing evidence to show that using green spectrum can help plants – blowing away what we thought we knew about growing cannabis.

Old technology HID lights did not offer the technology of LED lights, where cultivators can isolate and manipulate light. This control has sparked new research and growing methods as cultivators see how plants respond to different colors at different times in the growth cycle.

The common thinking, however, is that cannabis doesn’t use green light for photosynthesis – but this is simply untrue. And green light can be used at other times as well. 

So, what is green light? It’s light with a wavelength of 500-600 nanometers and it falls between red and blue light on the spectrum. No manufacturer sells specific green lights, because as of now, there isn’t a specific application for commercial cannabis growers.

However, just because there aren’t specific green lights available, cannabis cultivators can use full spectrum LED lights to get the green light wavelengths.

For cannabis growers, studies have shown that cannabis plants do use green light and it can penetrate into the lower part of the canopy. The addition of green light has been shown to increase the size and quality of lower colas thereby increasing the overall yield.

There is also research to show that it helps with photosynthesis. As cannabis plants have a dense canopy, the addition of the green portion of the light spectrum can be a benefit.

The Key Takeaway

While you could debate for days the best light spectrum for cannabis cultivation, it’s important to always have a balance. We know that increasing blue, red and far-red can play a role in cannabis cultivation (specifically on cannabinoids and terpenes), green light is an emerging and potentially game-changing addition to the spectrum.