supplemental lighting Adding Supplemental Lighting to Greenhouse Grows

Once considered two distinct schools of thought in horticulture, the lines between indoor and outdoor cultivation are continuously being blurred. Highly sophisticated, year-round cannabis greenhouse growing operations are at the forefront of this movement. Because, greenhouse gardening implements technologies of indoor growing while still utilizing the energy of the sun for essential plant functions. Perhaps the most vital technological application in modern day greenhouse cultivation is that of supplemental lighting.

The fusion of indoor and outdoor gardening methodologies comes about in greenhouse horticulture as these operations utilize the “best practices” of either school of thought. For a majority of growers, best practices concern operational costs, length of cultivation periods, and quality of harvest. That being said, year-round growing seasons and first-rate crops have stimulated the indoor market thus far.

Indoor vs Greenhouse

Looking at the practice of controlled environment agriculture for cannabis as a whole, horticultural lighting is one of the most important factors in dictating the outcome of a harvest. However, it is also one of the costliest elements of an operation. To illustrate, these operations come with an overhead of at least $400 per unit for 1,000 watt double-ended HPS lights and $800 for comparable LED’s. Taken to a commercial scale of indoor growing, this overhead can prove quite intimidating. Because, it is solely up to these artificial light sources to feed every square inch of a massive garden canopy. Moreover, the electrical costs of running these sorts of large-scale lighting setups can prove astronomical. To this end, 10,000 square foot warehouse grows report power bills to the tune of $12,000 monthly.

For greenhouse cannabis cultivation, critical applications of cultivation technology such as lighting have led to methodologies derived from a creative “give and take” between indoor and outdoor growing. As such, greenhouse gardeners now utilize light sensors, “black-out” tarp systems, dehumidifiers, supplemental lighting, and industrial heaters to mimic indoor environmental controls in outdoor settings. As a result, modern greenhouse horticulture has reached a pinnacle of crop production with the aid of hydroponics product technologies. These processes effect every facet of best practices related to both indoor and outdoor cannabis cultivation.

Interview with Spectrum King’s Brendan Strath

To shed some insight on the supplemental lighting topic, we reached out to the Brendan Strath, Senior Solutions Director and Grow Ninja for Spectrum King LED – a company known as “the pioneers of full spectrum LED grow lights.” Here is what Strath had to say:

MY: How important has supplemental lighting become in greenhouse cannabis cultivation and what are its primary benefits?  

Strath: “Supplemental greenhouse lighting is now an essential part of outdoor farming. It allows growers to keep crop production going on short winter days and bad weather days by providing a consistent light source in the greenhouse.

“Production costs are greatly reduced by combing sunlight with supplemental lighting. Each light is not on

full-power all day [when sunlight is at its strongest] and greenhouse lighting grids generally spread lights out more than with indoor growing. As such, lights run less and they cover a greater square footage, greatly reducing costs per square foot of canopy.”

MY: What would you say is the biggest benefit of supplemental lighting in cannabis greenhouse growing?

Strath: “For me, the use of supplemental lighting in greenhouse growing has its largest impact concerning carbon footprints. Using the greatest light source in the world [the sun] for the heavy lifting and just supplementing a few hours a day when sunlight intensity is low is a much greener way of producing crops than with straight indoor cannabis growing. Also, with this method you can produce quality crops all year round with lower production costs.”

MY: Is the use of supplemental lighting more prominent with growers in certain regions of the United States than others? If so, why?

supplemental lighting

Strath: “That’s a great question and one that is often overlooked. Yes, at first-glance some regions are better suited for greenhouse growing than others. Any geographies with extreme weather conditions (aka cold, wind, snow, etc.) are perfect for greenhouses, they offer environmental protections for crops while utilizing sunlight. Grows in these regions without consistent sun also benefit the most from supplemental lighting.”

“However, with a little thought and ingenuity you can do well with greenhouse cultivation just about anywhere on earth.”

MY: Are LED’s gaining popularity among greenhouse cannabis growers? If so, what are the benefits of using LED’s as opposed to other lights?

Strath: Absolutely! The technology that was frowned upon by growers a few years ago is now becoming their go to light source. Spectrum King can cater lighting intensity and spectrum to specific crop requirements with LED’s, whereas bulbs simply can’t fine tune their spectral output. While you may be able to lower the intensity of traditional HPS and MH bulbs, the system is not as fluid and dependable as with LED’s. Also, there are the obvious power savings and longevity that LED’s offer.”

MY: Many see automated greenhouse growing as the “future of the industry” because it utilizes controlled environment agriculture with the added perk of sunlight. What are your thoughts on this?

Strath: “I couldn’t agree more with that statement. Whether it’s medical crop or food production, people want healthier choices that are also cost effective. By keeping production costs down through greenhouse growing we can offer fresher and healthier food and medicine. To me, that’s an obvious no-brainer.”


Modern greenhouse cultivation with the added bonus of supplemental lighting truly diversifies horticultural applications outdoors. Also, as Strath had mentioned, this form of growing is not only economically viable, it also more environmentally friendly. With this sort of best practice, technological advancements have allowed cannabis greenhouse growers to devise cultivation methods that can realistically sustain the industry well into the future. Finally, novice and expert growers alike can utilize supplemental lighting to produce fresh medicines and crops year-round.

This article first appeared in the January 2019 edition of Maximum Yield Magazine.