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Let the Light Guide You

Maximizing cannabinoid production simply by using light

What if you read that you could boost your cannabinoid production by 5-7%? Voodoo? No. Alchemy? No – that’s an overused word transmogrified to mean something very different from its real definition.

Better yet, what if you read that your plants needn’t produce a single, albeit majestic cola? What if you could have, I don’t know, forty colas on a plant? The ravings of a madman? A portent of Armageddon?

Relax. This is reality, and these possibilities are very real.

You may recall an article with Noah of Black Dog LED where we rapped about research that they’ve conducted that optimized ambient air temperatures in a growroom. Black Dog found that light-emitting diodes (LEDs) don’t heat plant leaves like other lighting options, which contain unnecessary wavelengths of light (e.g. infrared or green) that plants cannot convert to energy. This excess of input energy causes the plant leaves to heat up, which is okay to a degree, since plants have optimal metabolic temperatures.

Black Dog LEDs don’t emphasize those wavelengths, so plants grown under them require higher ambient air temperatures. But growhouses have tons of excess heat. They usually need to be cooled, so limiting how much energy must be expended to cool a grow obviously reduces overhead costs.

I wanted more, so I spoke with Kevin Frender, the Chief Science and Technology Officer of Black Dog. Like an electromagnetic radiation puppeteer, Kevin has been mastering the growing of various plants under artificial lights for 30+ years, including a vivacious display of tropical fruits right in Black Dog’s Boulder office. And while he was between day jobs, he serendipitously incorporated a Black Dog LED into his cultivation hobby, which has since become a career.

So, this time, I wanted to tap into the roots of his knowledge regarding how one can best harness the light for cannabis and hemp cultivation (or really any botanical, but you don’t read T&T to talk about vegetables).

LEDs have presented a common alternative to high-pressure sodium (HPS) lights. The problem, according to Kevin, is that the technology was originally researched by NASA (National Aeronautics and Space Administration). “The original LEDs couldn’t grow lettuce, which is a low light plant,” Kevin explained. “NASA did a lot of research on growing lettuce in space. Most other LED companies have based their tech on these studies. Therefore, they’re using technology that has been optimized for maximizing leaves, not flowers, which require a different light spectrum.”

Obviously, despite propaganda likening cannabis to the Devil’s Lettuce (or the Devil’s Kale to be more modern), comparisons of the two plants don’t go very far. A cannabis grower wants flowers not leaves. So, it’s understandable why implementing the best light wavelengths for specifically maximizing cannabis flower and resin production would amplify the medicine and the money coming from a harvest. The numbers of trichomes increases as does the concentration of cannabinoids and terpenes therein. “Unlike every other technology, we can manipulate the spectrum and spectral ratios to be what we want,” Kevin proselytized.

Kevin and I started at the beginning, with thoughts of the primordial. “Plants evolved into long- or short-day light requirements,” Kevin began. “There are different hormonal responses to the light which cause the plants to react in fundamentally similar ways to different colors of light and the ratios between the colors of the light.”

Blue and red wavelengths and their ratio to each other helps dictate how a plant will grow. “If plants don’t see as much blue light as red light, they think they can’t see the blue sky,” Kevin explained. “The ratio of red to blue determines how plant stems elongate. And if you grow cannabis under those ratios, you’ll get big leaves on tall plants, but you’ll see less flowers, because more energy is going towards leaves and stems.”

In addition to this, Kevin cautioned that a plant’s stems can crack under their own weight because the stems are thinking there’s something up above and they’ll need to grow taller to reach it. The red-to-blue light ratio tells them this.

Black Dog LEDs have designed their light spectrum to keep internodal spacing reduced, meaning more leaves per branch; for more flower sites at leaf nodes; and to produce shorter, more manageable plants, such that there’s better usage of nutrients. Their LEDs target energy where it needs to go to best optimize flower, and therefore, resin production. HPS lights force plants to use energy in stems due to the excess of red light and lack of blue.

We’re about a month out from a time when pine trees are hacked down, thrust into living rooms, and garishly decorated with weird assortments of edibles like popcorn and candy, and inedibles like glass balls and phony snow. So, a conversation on apical dominance was not only elegantly nerdy, but also quite timely.

Apical dominance forms the point (apex) in plants like the traditional Christmas tree. “Plants have a hormone called auxin that inhibits the growth of other branches besides the apical meristem,” Kevin explained. This suppression causes the plant to grow upward such that it can outcompete its neighbors. The problem is that this requires energy that could be used elsewhere for desirable effects like more flower production.

“Plants with strong apical dominance can get a gigantic primary cola, but much smaller flowers on the other branches,” Kevin added. “But you can control apical dominance using the light spectrum such that plants are shorter, bushier, with branches unimpeded by auxin. Instead of generating one cola, you might have forty.”

The Black Dog LED encourages side branches to grow equally. Another innovation is the inclusion of ultraviolet (UV) wavelengths. “We’re the only LED grow light company that actually put UV into the lighting,” Kevin discussed. “We wanted to design a light source that best captured the wavelengths of natural sunlight.”

The energy of the Black Dog LED contains about 6% of UV photons. “While it might not be necessary,” Kevin explained, “photomorphogenesis (the development of form and structure in plants which is affected by light) of plants through different wavelengths produces different compounds, such as hormones to control the spacing of nodes, or cannabinoids.”

Cannabinoids are a natural sunscreen, protecting cannabis plants from potentially damaging UV rays. When Black Dog had their test plants analyzed, they found a 5-7% increase in THC (delta-9 tetrahydrocannabinol) and CBD (cannabidiol) because the light is triggering the plant to produce these natural sunscreens.

In addition to this defense, UV light serves to bulk up cell walls, making them more impenetrable. “Plants try to protect themselves with thickened cell walls so they’re more resistant to bacteria, fungi, and insects,” Kevin said. “Most artificial light produces thin cell walls since UV light isn’t involved, which means plants are more susceptible to diseases like powdery mildew.”

There are other benefits to adding UV wavelengths. When a UV photon interacts with a leaf, for example, it loses energy. The next shortest wavelengths are purple and blue, and then the rest of the ROYGBIV hues you’ve known since grade school, just in reverse order. The point is that, because of the higher energy of the starting UV photon, it can continuously catalyze photosynthetic processes as it interacts with the plant and simultaneously loses energy. Longer wavelength, lower energy visible light photons will be spent sooner.

“If you turn the UV off,” Kevin added, “you’ll see less photons penetrating dense plant canopies. With it, you’ll grow a thicker canopy and still reach lower buds that are less larfy. You can get top-shelf quality buds throughout the entire plant. You can get two-to-three times the industry standard yield per square foot of cannabis just by manipulating the light spectrum.”

One unintended but wonderful side effect Black Dog witnessed was the targeting of colors of light that chlorophyll can directly absorb. “Plants are horribly inefficient for capturing light and converting to sugars for growth,” Kevin explained. Cannabis is about 2-3% efficient; sugarcane is 8-10%. To make it easier, you can target colors that plants can directly use. Pure chlorophyll primarily uses blue and red instead of yellow and green regions of the spectrum, the latter of which thus comprises just 1/5th of the intensity of the blue and red photons in our LED.”

One reason Black Dog added these yellow and green wavelengths wasn’t for the benefit of the plants, but rather, for the growers. “The light was kind of harsh on the eyes,” Kevin exclaimed. “We added green and yellow light to get the threshold up so our brains can adapt. Everything used to look purple, but these spectral tweaks made it look white to the human eye, whereas regular cameras still see purple.”

While hemp cultivation has traditionally been endeavored outdoors, the need for more growing cycles or completely indoor operations is escalating. Black Dog reports hemp farmers are using their LEDs for supplemental lighting when growing hemp starts indoors for subsequent transfer into nature. “These plants are short, bushy, and heartier when you put them into a field, and endure less damage from wind,” Kevin commented. “You also don’t have to harden them off, since the UV wavelengths are always present. Plants can get sunburned just like us when you bring them into UV light because the starts under artificial light haven’t seen these wavelengths.”

The fountain of light and energy and knowledge put out by Black Dog is perpetually growing, much like that plant exhibiting apical dominance. But they’re not pumping any brakes. An indoor hemp cultivation facility for research and development is currently under construction at their Boulder, Colorado headquarters.

Stronger, healthier plants with perhaps 40 colas, more flowers, a 5-7% boost in cannabinoid potency, and increased resin production within the trichomes? Am I dreaming? That scene seems to paint the greatest forty-headed, compassionate floral hydra to venture into anyone’s dreams. But one’s dreams can indeed be achieved… all you need is a little guidance and illumination. Luckily, Black Dog offers both.

About the author

Jason S. Lupoi, Ph.D.

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