Better understanding of cannabis-related photobiology is helping LED grow light manufacturers produce lighting that increases crop yields and perhaps more importantly, cannabis quality.

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.

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.

Dr. Zacariah Hildenbrand has published more than 50 peer-reviewed scientific journal articles and textbook chapters in the fields of cancer biochemistry, environmental science, and natural products. He is also an editor of a new textbook with Elsevier titled ‘Advances in Chemical Pollution, Environmental Management and Protection’, and was recently nominated for the Humanity in Science Award, which recognizes scientists for their altruism and innovation. Dr. Hildenbrand has advised several companies through the development of novel technologies for remediation and waste recycling, and enjoys new research challenges that carry deep social significance. Dr. Hildenbrand is currently the chief technical officer at Inform Environmental, and he is an advisor to the Tall Trees LED Company.

Robert Manes is an entrepreneur and lighting designer dedicated to furthering knowledge of lighting as it relates to medical cannabis. He has developed and manufactured solid-state lighting (LEDs) for horticultural purposes since 2006 and his designs were used to win awards at several national and international “Cannabis Cups”, including a 1st, 2nd and 3rd place in Arizona’s ERRL cups in 2017 and 2018. Robert is CEO of Light Engine Design Corp ( and Tall Trees LED Company (, producing LED grow lights for the retail and commercial grow markets. His new book, “How to Grow Marijuana with LEDs” was released in March and is available at several online stores, including Amazon and Barnes and Noble.

Very good analysis. LEDs are ready for the primetime now and offer many benefits over the alternatives, imo.

Hi, It’s awesome analysis. Thank you for sharing your thoughts. I have got some good ideas to build my own! Thanks again!

Like you, I’d much rather buy LEDs than florescent fixtures, but I also agree that at a certain point it has to make financial sense. LEDs are really starting to make sense for standard house lights, but what about grow lights?

When we upgraded our florescent grow lights last spring from old T12s to much-higher-efficiency T5s, I did some pretty extensive research and came to the conclusion that LEDs didn’t make sense for the home gardener unless you were growing a certain highly valuable cash crop entirely indoors.

In this kind of application, LEDs really are run at a quantity where their superior efficiency pays for itself quickly. LEDs also offer other advantages over fluorescents, such as the ability to control the spectral content of the light. This allows the indoor farmer to provide her plants with optimum lighting conditions at every phase of life, from seed to fruit (or – who are we kidding – bud).

Okay, but what about folks like us who really are just starting tomatoes (not “tomatoes”) a few weeks early. We want to save a dime or two on electricity and ideally avoid the toxic contents of a fluorescent tube. Are LEDs right for us?

Lets look at the math, if the single T5 lamp runs at 54w (plus a couple watts for the driver), and you are using 4 lamps in the fixture, then at a rate of $0.12 per Kw hour, you’re spending about $4.35 for 14 days of light for that one fixture at 10 hours per day.

A similar LED fixture may run at about half the output, or 113w compared to the 4lamp T5, so expect a little over $2 savings from the one fixture over the same time period.

I am a farmar and grow cannbis in a green house, I was wondering “If I could keep my cropes healthy’ but after reading your article where you have mentioned about LED lights and its impect on cropes, I feel amazing. Thanks for the beneficial information.

Really amazing post, Informative, helpful and easy to understand. I always try to get more information about grow lights and grow methods and you can say that I try to catch all about this. so this post is perfect for me. Keep sharing. is proud to present this webinar brought to you by Deibel Laboratories, Inc. The validity of test results relies heavily on how well the collected samples represent the product lot. A sampling plan provides the underlying methodology for where, when, and how to collect samples. In this session Brian Farina, the Sr. Director of Technical Services for Deibel Labs, will provide some introductory information on what a sampling plan is, how they’re developed, and some best practices for collecting different cannabis sample types. is proud to present the 2nd Annual Cannabis Cultivation Virtual Conference. This complimentary collection of webinar presentations will help attendees better understand a variety of techniques, best practices and new technology in the field of cultivating cannabis. Attendees registering for this complimentary series of webinars will get access to four veterans of the cannabis growing industry, who are available for Q&A after each presentation. In addition to getting the opportunity to chat with these subject matter experts on June 19th, a recording of the presentations will be made available to all who register. As the cannabis growing industry flourishes in the United States and internationally, a number of growers are expanding their operations to meet higher consumer demand. Growers are in a competitive new market and will benefit from maximizing efficiency. 4 complimentary webinars, all on the same day: Don't miss this chance to see cannabis growing professionals share their expertise and the opportunity to ask them questions. Sign up today!

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