When growing cannabis — or any other plant, really — lighting matters, and not just in terms of intensity. The color and wavelengths of the light your plants receive, also referred to as spectrum lighting, directly impacts how those plants grow and develop, for better or for worse.
Anthony Domangue, Cannabis Cultivator and Consultant at Fohse, says, “The sun is like the main, great grow light, and you often hear people say it has a full spectrum. So when people try to create grow lights, they do their best to emulate the sun as close as they can, or combine that with their personal goals.”
When used correctly, spectrum lighting can increase your yield and produce higher-quality cannabis. When neglected or used incorrectly, it can cause you to miss out on your crop’s potential or even damage your plants.
Read on to learn more about how spectrum lighting affects cannabis growth and how to choose the right spectrum light fixtures to maximize your yield.
Spectrum Lighting: The Basics
To the naked eye, many lights look very similar in color, but they often lean in one color “direction” (e.g., blue or red) over another.
Domangue explains, “Certain spectra can be beneficial during certain times, and they can also be to the detriment of the same crop, depending on how old they are.” Different colors impact plants differently, and that impact can change as the plants grow.
How Does Color Impact Cannabis Growth?
During the vegetative stage of cannabis growth through early flowering, Domangue says, “A higher portion of blue light within a full spectrum is best.” For indoor grows and low-ceiling spaces, especially, it tends to yield shorter, more compact plants, while red and pure blue lights tend to produce stretchier, “leggier” plants and can even cause bud bleaching.
However, in the mid- to late-flowering and reproductive stages of plant growth, too much blue light has been linked to a decrease in yield. In these stages, plants benefit from lights that have a fair amount of red.
Domangue explains that Fohse designed its flagship “seasonal” spectrums with these impacts in mind. The fixtures begin with plenty of blues in spring (vegetation and early flowering), shifting through summer (mid-flowering) and into autumn (end of flowering cycle) to end with a greater concentration of reds.
Green light, on the other hand, doesn’t seem to affect plants as strongly as other colors, so it’s often used after the facility lights are turned off to avoid stressing the plants with excess light. “Generally speaking, plants don’t absorb much of that green wavelength,” Domangue says. “So it’s a very safe way for people to work while the plants are supposed to be sleeping.”
That said, more research is needed to know the full effects of using green light, especially when other lights are on.
What About UV Light?
Domangue notes that there’s a lot of speculation and anecdotal evidence about the application and impacts of ultraviolet (UV) light on cannabis growth. While many believe UV exposure to be beneficial, some studies have found it to have little or even negative impact on yield.
Ultimately, research on the role of UV light in cannabis production is inconclusive. Further studies are needed to determine its full benefits, detriments, or other effects.
Fixed vs. Variable Spectrum Lights
When choosing spectrum lighting for your grow, there are two main options: fixed spectrum or variable spectrum.
Fixed spectrum lighting is the cheaper of the two but more labor-intensive . Fixed spectrum lights, as the name suggests, are “fixed” on one color spectrum. That means you’ll have to either move plants from one light to another as they grow. Under HID systems, this means changing out the bulbs for each new stage of growth.
“I’ve been in facilities where it’s time to flip plants to flower and, depending on how many people you have, it could take a few hours,” Domangue points out. “That’s expensive if you’re doing that every week — or however frequent your harvest schedule is — it gets costly with the labor.”
Variable spectrum lights, on the other hand, are able to change spectra (also called “spectral tuning”) as the plants grow. While they’re more expensive, they’re worth the investment for the decrease in labor cost, greater control over the light your plants receive at any given time, and increase in the quality and yield of your final product.
For those interested in light fixtures equipped with spectral tuning, Domangue recommends Fohse’s A3i for high-ceiling facilities, Scorpio series for low-ceiling spaces or rack systems, and Aries for home growers.
Spectrum Lighting for Maximum Yield
Spectrum lighting, when used correctly, is a critical component of cannabis plant growth, so it’s important to know which spectrum lights to use and how and when to use them for maximum yield.
At HYC, we’re committed to helping you set your cannabusiness up for success. That’s why we’ve carefully vetted numerous lighting options to find the very best. Through this process, we’ve found Fohse lights to be the best in terms of spectrum, intensity, efficiency, integration, and longevity.
Want to get a custom grow design or spectrum lighting plan, or to place a bulk order? Contact us today!