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Are LED Grow Lights Worth It?

By Dr. Zacariah Hildenbrand, Robert Manes
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There really is no question that Light Emitting Diodes (LEDs) work, but just how well do they work?

For the last 50+ years, indoor cannabis cultivators have used High Pressure Sodium (HPS) lights to illuminate their flowering crops. This technology was developed for, and is still used, as street lighting and there really hasn’t been a fundamental change to the output in the last half century.LED technology showed great promise to solve some of the primary drawbacks to the use of HPS technology for indoor cannabis cultivation. 

We are often asked why this technology was used to grow cannabis, and the answers are simple: 1) due to strict legislation and even stricter penalties for growing cannabis, growers wished to move their crops indoors, and, 2) there really hasn’t been another technology that would allow us to cheaply place 400, 600, or even 1000W of light on a crop. In addition, HPS technology is rich in certain frequencies of red light, which is so important to flowering crops. Unfortunately, HPS lamps have their drawbacks, such as high heat output and lack of other “colors,” along the lighting spectrum. In fact, up to 95% of light produced by an HPS lamp is emitted in the infrared range, which we perceive as heat.

Enter the Light Emitting Diode. LED technology showed great promise to solve some of the primary drawbacks to the use of HPS technology for indoor cannabis cultivation. The ability to manipulate spectrum, precision delivery of light, elimination of dangerous heat, and lack of substantive toxic chemical makeup are a few reasons to deploy LEDs. However, as with any new technology, there were some significant hurdles to overcome.

Early experimentation using Light Emitting Diodes (LEDs) to grow cannabis, suffice to say, did not go well.  Poor performance, misleading advertising and equipment failures plagued the first mass-produced LED grow lights. The aspect of poor performance can be blamed on several factors, but the most prominent are very low efficacy, in terms of light produced per Watt consumed, and incorrect application of spectrum (color) for horticultural purposes. Causes of “misleading advertising” was a mixed bag of dubious sales pitches and lack of understanding the technology and of horticultural lighting requirements. Additionally, there certainly were some quality control issues with LEDs and electronics equipment in general, especially from offshore manufacturers in China and Korea.

A plant in flowering under an LED fixture

That legacy of poor performance still has a partial hold on the current indoor cannabis cultivation industry. Many of the current “Master Growers” have tried LEDs at some point and for the various reasons mentioned above, reverted to HPS lighting. Some of this reluctance to embrace LEDs comes from unfamiliarity with application of the technology to grow better cannabis, while some can be attributed to stubbornness to deviate from a decades-long, tried-and-true application of HPS lighting.

Certainly, growing with LEDs require some changes in methodology. For instance, when using true “full spectrum” grow lights, more nutrients are consumed. This is caused by stimulation of more photoreceptors in plants. To further explain, photoreceptors are the trigger mechanisms in plants that start the process of photosynthesis, and each photoreceptor is color/frequency-dependent. True full spectrum LED systems fulfill spectrum shortages experienced with HPS technology. Anyone that grows with LEDs will at some time experience “cotton top,” or bleaching at the upper regions of their plants.  Increased nutrient delivery solves this issue.

As we continue to uncover the vast medical potential of cannabis, precise phytochemical composition and consistent quality will become all-important.While the industry is still saturated with confusing rhetoric and some poorly performing equipment, LEDs are gaining momentum in the cannabis market. LED efficacies have increased to levels far greater than any other lighting technology. Broad spectrum white and narrow-frequency LEDs in all visible (and some invisible to the human eye) colors are being produced with great precision and consistency. Quality control in manufacturing is at an all-time high and longevity of LEDs has been proven by the passage of time since their introduction as illumination sources.

As the world embraces LED horticultural lighting, probably the most encouraging news is that current and upcoming generations of cannabis growers are more receptive to new ideas and are much more tech-savvy than their predecessors. Better understanding of cannabis-related photobiology is helping LED grow light manufacturers produce lighting that increases crop yields and perhaps more importantly, cannabis quality. As we continue to uncover the vast medical potential of cannabis, precise phytochemical composition and consistent quality will become all-important.

Obviously, the indoor cannabis industry is expanding rapidly and this expansion raises deep environmental concerns. More power is being used for indoor lighting, and for the cooling required by this lighting. Power systems are being taxed beyond forecasts and in some cases, beyond the capabilities of the infrastructure and power companies’ ability to produce and deliver electricity.  Some states have proposed cannabis-related legislature to limit power consumed per square foot, and some are specifically requiring that LEDs be used to grow cannabis. While some business leaders and cultivation operators may groan at the acquisition cost and change in operating procedures when deploying LEDs, common sense states that it is imperative we produce cannabis applying the most environmentally friendly practices available.

The Great LED Debate

By Aaron G. Biros, Aaron G. Biros
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The preferred choice for indoor cannabis growing has long been high-pressure sodium (HPS) 1000-watt light bulbs during flowering. Light-emitting diodes (LED) are quickly changing the indoor farming landscape with innovative technologies and promising energy savings. Many think the technology still needs time to develop. There are certainly many pros and cons to switching an indoor cultivation facility from HPS to LED lighting systems.

Steve Kruss, president of Light-Waves Electronics, Inc., gave a comprehensive analysis of the advantages and disadvantages of various light sources at the CannaGrow Conference and Expo. “The first adopters [of LED light technology] more than two years ago did not get the results they wanted, so many growers gave them a bad rap very early on,” says Kruss. His discussion delved into the pros and cons of both LED and HPS lights in growing cannabis.

lightwavesinc
Light-Waves Electronics Inc. LED fixtures being installed in a cultivation facility.

It is important to highlight the weaknesses in many common HPS systems and the possible solutions that LED technology could offer. According to Kruss, HPS lights do not match the light spectrum’s photosynthesis curve that plants need to absorb energy. HPS lights give off a tremendous amount of heat that requires more energy to cool a facility down with an HVAC system, increasing energy costs for growers. Since LED’s use 50% less wattage, they produce approximately 50% less heat, significantly reducing cooling costs. HPS light bulbs need to be replaced multiple times per year. Quality LED fixtures can last more than 50,000 hours, or roughly eleven years. “The reality is HPS is putting a lot of light out but that energy is wasted because so much of it is in a light spectrum that plants do not absorb,” says Kruss. Perhaps most important is the lack of ability to vary the light spectrum; any light that HPS bulbs produce that the plant does not absorb is essentially wasted energy.

LED light bulbs provide a solution to the wasted light in HPS by targeting the particular spectrum that plants need for photosynthesis. By targeting the photosynthetically active radiation (PAR), roughly 400-700nm, LEDs can effectively mimic the sun’s ability to produce the wavelength of light specifically needed in a certain stage of cultivation. The absorption spectra and action spectra are wavelengths of light preferable for harvest as well as plant growth and metabolism, respectively. LED manufacturers and growers commonly try to harness the Emerson Effect, which uses red (670nm) and far red (700nm) to increase the rate of photosynthesis.

A plant in flowering under a Light-Waves Electronics LED fixture
A plant in flowering under a Light-Waves Electronics LED fixture

The benefits of LED lights in growing cannabis are numerous. The primary benefit is that it provides light at the specific wavelengths chosen to match the specific needs of plants. When finely tuned, LEDs can influence the growth process by slowing down vegetative plant growth and inducing flowering when appropriate. LEDs are more energy efficient than their counterparts partially because they give off substantially less heat in the beam itself, reducing cooling costs. Some growers use LEDs together with HPS lights, some use LEDs with natural sunlight in a greenhouse setting and some use strictly LEDs for the entire growth cycle. Each cultivation operation has its own budgetary restraints and structural limitations, but energy efficiency is one area that all growers should look to improve. According to Adam Koh, chief cultivation officer of Comprehensive Cannabis Consulting (3C), indoor growers can get away with T5 fluorescent lamps (which do not consume much energy) throughout the vegetative process.

For some, the debate is over and growers recognize the added benefits that LEDs bring to growing cannabis. According to Kruss, LED technology is almost there. “In terms of yields, LED lights are providing around 75% of the weight that HPS produces, but on the vegetative side, the growth is considerably faster which could make up for that weight loss with faster grow cycles and an extra harvest,” says Kruss.

Talltrees
An LED cultivation operation set up by Tall Trees LED Company

Adam Jacques, award-winning grower and founder of Growers’ Guild Gardens, has used LEDs in tandem with sunlight. Him and his team have bred and grown cannabis in indoor, greenhouse and outdoor operations. “I love the huge steps that some LED manufacturers have made in the past year,” says Jacques. “When I utilize them within a greenhouse setting I really like the product it grows.” Jacques’ findings in the field echo Kruss’ statements that LED lights have made considerable progress very recently. “It does take a little dialing in due to the plants’ increased feeding regiment, but it is a small price to pay for all of the benefits we see,” adds Jacques. His success with the new technology is representative of a larger trend; more and more growers are beginning to implement LEDs in some form.

Some claim the yield is less from LED lights during flowering.
Some claim the yield is less from LED lights during flowering.

Maxx Wiley and Robert Manes, co-founders of Tall Trees LED Company based in Arizona, believe their technology is on par with the yields other growers are getting with different light sources. “We conducted heads-up tests with our 500-watt LEDs versus other 1000-watt HPS bulbs and have seen very impressive results,” says Wiley. “The plants under our lights were consistently getting more weight and more flowers; the flowers appeared smaller but were actually denser and heavier in reality.” Wiley’s company makes commercial LED luminaires that are IP 65 waterproof rated and he claims they never had any issues with failures. The technology uses no moving parts to cool the lights, just metal clad circuit boards, heat sinks and conductive thermal-bonding materials. “We have had customers run potency analyses and have found tremendous variation in plants grown with HPS,” says Wiley. “We see more compound production and more consistency crop-to-crop with our LED technology.” There are currently a handful of manufacturers bringing innovative designs to market.

A cultivation operation in Maine using GS Thermal Solution liquid-cooled LED fixtures
A cultivation operation in Maine using GS Thermal Solution liquid-cooled LED fixtures

GS Thermal Solutions, based in Connecticut, manufactures 1000-watt LED fixtures that are liquid-cooled. The company makes lights that are fully adjustable, so growers can dial in each spectrum of light intensity independently and tailor to specific strains as well as stages of growth. According to Rick Rhyins, vice president of sales at GS Thermal Solutions, the liquid cooling technology allows for a much longer lifetime of the LED and a much more efficient energy consumption. “Our technology addresses the shortcomings and previous problems with early generation LED models,” says Rhyins. Coupled with facility automation, GS Thermal Solutions uses a central control system to monitor cooling, light intensity and spectra, nutrient monitoring and feed control.

Yet some are still skeptical of the LED lighting in today’s market and feel the technology is not there yet. Nic Easley, chief executive officer of Comprehensive Cannabis Consulting (3C), has brought over sixty cultivation operations to market and is hesitant to endorse the technology at this point. “I will never be an early adopter when it comes to new lighting technology and I feel we are at least a year out from seeing consistently efficient LED lighting,” says Easley. “There are still a lot of false claims out there and I want to wait until I see repeatable results on a small scale before I feel comfortable endorsing LED lights for cannabis cultivation.” While companies will continue to innovate lighting solutions for indoor cultivation, in many cases (but not all) it seems using the sun to grow cannabis would be more energy efficient.