USING LIGHT SPECTRUM FOR HIGHER YIELDS, HIGHER POTENCY AND BETTER LOOKING, TASTING AND SMELLING BUDS.
While there is still many unknowns about cannabis and cannabinoids due to its prohibition and lack of studies as a result, more and more studies about its growth patterns and optimal conditions have been popping up in the past 10-15 years. The result of this gathered information brings forward an issue that has long been recognized by cannabis growers - most grow lights and the spectrum ranges they offer force a trade off between dense high yielding buds that are average in their look, smell and cannabinoid density, or average yielding buds that are beautiful, fragrant, and can have up to 30% more cannabinoid density. In this article I will outline (a) the benefits of different ranges of light on cannabis plants, (b) grow lights, optimal yield results, and the spectrum trade off, and (c) what lights offer the best buds in terms of yield, look, potency, taste and smell. By the end of the article you will know what you need to do to optimize both flower growth and cannabinoid density in order to grow top shelf dispensary level buds.
A. The Benefits Of Different Spectrum Ranges On Cannabis Plants
The following paragraph may be a lot for some readers, but hang in there, I’ll summarize!
Yellow and white light is a commonly used light range for growing plants in general, and in cannabis this spectrum range promotes germination and long stems. During flowering a small level of this type of light can also boost flower production.
Of all the spectrum ranges, the least is known on the effects of green light on cannabis plants, though the consensus is that it is beneficial to have at least a small amount. The common theories are that green light reflects off the plant canopy and into the shadowy areas and backside of plant foliage. It is also believed to counter most of the effects of blue light during the plants vegetative stage.
It is fairly common knowledge that red and far red spectrum light promotes flower growth during this stage, and that blue range light during the vegetative stage promotes stem and healthy root growth. What is less known is that too high a ratio of red-to-blue light during the vegetative stage can cause unwanted stretching in your plants and if this ratio is too low during flowering it will result in lower yields.
Inversely, if the ratio of red-to-blue light is lower during vegetative it promotes shorter, stouter plant growth with tight inter-nodal spacing - ideal for indoor growers. A high ratio of red-to-blue during flowering promotes greater bud production and height growth. Note that too much far red or infrared light during this stage could lead to unwanted stretching.
Lastly, in recent years much has been learned on the effects of blue, UVA and UVB spectrum light on cannabis growth. For instance exposing the plant to greater ratios of blue light during flowering is believed to increase the density of flavonoids, terpenes and cannabinoids. Meanwhile exposing the plant to UVB light, for instance in the last 3-5 weeks of flowering, can result in an increase in trichome production and therefore greater overall production of these compounds by up to 30%.
SUMMARY: There are two important points to take away from all of this. One, similar to how solar light intensity changes with the seasons, your cannabis plants require different intensities and ratios of light during each stage of growth in order to produce optimal results; and two, the resulting effects of red versus blue spectrum light on the plant during the flowering stage are conflicting. A high ratio of red-to-blue light results in high yields but less essential compounds, while lower ratios of red-to-blue promotes greater essential compound density but less overall flower density and yield. This is the cannabis ‘spectrum trade off’ and leads me to the second part of this article.
B. The Issue With Modern Grow Lights: Tackling The Spectrum Trade Off
Today’s grow lights are fairly rigid in their design and use. Most offer up a single spectrum designed to be used throughout each stage of plant growth, with directions to raise or lower the entire light in order to adjust intensity, but this does not change the spectrum ratio at all. This is not ideal because of the contradicting effects red and blue spectrum light has on the plant at each stage. Essentially the lighting company has made the decision of what your goals are for your grow: high yields, good looking and smelling buds, or potency.
Alternatively, some other lighting companies offer up spectrum customization in the form of veg and bloom on/off switches. This brings up a whole other set of issues- for instance too low a ratio of red-to-blue light can slow plant metabolism leading to less foliage and therefore reduced levels of photosynthesis, and can lead to a bunch of other developmental issues such as leaf edema (when the leaves swell up). Most growers with these switches have them both active for most of their grow, leading back to the trade off issue.
Lastly, and what I will be discussing in the next section of the article, is a rare third group of grow lights that have light intensity and spectrum adjusters. These options allow for complete control over both spectrum and intensity without the need to turn a certain spectrum range off completely. There are not many of these lights out there, but they are certainly the future of grow lights as we learn more about what this plant needs to produce the best quality buds possible.
C. The Solution For Optimal Yields And Peak Cannabinoid, Flavonoid and Terpene Production
What cannabis growers need is a light that allows spectrum ratios to be controlled in order to optimize the goals of each stage of growth. There are very few lights like this, but they do exist and are called hybrid, or custom spectrum grow lights. The ones I know about are the KIND K5 series and FOURBUDZ pro series, each offering 4 channel settings that control a different spectrum range. The price difference is notable, even though the lights are actually very comparable - I use a FourBudz pro3 for this reason. I’ll explain the benefits of custom spectrum lighting by explaining how I use it to grow my plants.
When my plants are seedlings, my goal is to promote healthy root and stem growth while avoiding stretching or photobleaching. So for this stage I turn the intensity of blue light and UV light to 30% and red to 15%, then double these numbers after about a week or so.
Once the plant has reached the vegetative stage it can handle full intensity blue spectrum light, but I still keep both red range light channels at 60% to promote more compact internodes and less potential stretching caused by too much infrared light. The level of red light still balances out plant metabolism to keep photosynthesis levels high.
Once I switch to a 12-12 lighting schedule I will ramp up red light intensity to 80% and keep blue and UV light at 100%. This ensures a comfortable photoacclimation of the plant to a full intensity light schedule.
A few weeks into the 12-12 switch I will turn the grow light up to 100% intensity for all channels. The plant is working overtime during this period of growth and needs energy from any spectrum range it can get.
In the last stage, and arguably the most important stage in terms of light spectrum ratios, I keep all reds at 100% to keep flower production levels high. I also keep UV and white light at 100%, which forces the plant to create new trichomes and therefore generate more cannabinods, terpenes and flavonoids. Lastly, I turn mid-range blue spectrum light down to 70%, which adjusts the spectrum slightly to promote greater growth and density of the plants flowers. All in all, this leads to high yields AND high potency in buds that look, smell and taste like top shelf dispensary product.
I hope you hung on and read the article in its entirety. It can be a lot for those new to growing, but lighting is also the single most effective factor in manipulating harvests and creating high yielding top shelf buds. If you just skipped to the conclusion, maybe you’re one of the many growers that simply does not care how top shelf buds occur- but rather that they do with your plants (Just tell me what I need to do!). If that is you, then the bottom line here is go out and buy a custom spectrum grow light. There are a few companies that offer them, like KIND and FOURBUDZ, and they typically come with guides on how to adjust channels at each stage of growth for optimal harvest results. I was able to get the spectrum settings I discussed above from the FOURBUDZ website (click here to view), and the harvest results so far speak for themselves. Click here for a link to the FOURBUDZ pro3 product description.
'Prof' is a professionally trained Canadian teacher with a love of horticulture and advocate of the democratization of cannabis cultivation, especially for medicinal purposes.