Combining Sunlight and Grow Lights: Supplemental Greenhouse Lighting

Once considered two distinct schools of thought in horticulture, the line between indoor and outdoor cultivation is being blurred. Highly sophisticated, year-round greenhouses are at the forefront of this fusion movement as they utilize the best practices of both methodologies in a creative give and take. These operations utilize the sun’s energy to power essential plant functions while implementing indoor growing technologies like light sensors, blackout tarp systems, dehumidifiers, and industrial heaters to mimic indoor environmental controls in outdoor settings.

Supplemental Lighting

Perhaps the most vital technological application in these modern-day greenhouses is that of supplemental lighting. In indoor gardening, lighting is one of the most important factors dictating the outcome of a harvest. However, it is also one of the costliest elements of an operation, with an overhead of at least $400 per unit for 1,000W double-ended high pressure sodium (HPS) lights and $800 per unit for comparable light emitting diodes (LEDs). Taken to a commercial scale, this overhead can prove quite intimidating as it is solely up to these artificial light sources to feed every square inch of a massive garden canopy. Then there is the astronomical cost of running the lights in these large-scale set-ups. Some 10,000-square-foot warehouse grows have reported power bills to the tune of $12,000 monthly.

However, modern greenhouses use best practices from both indoor and outdoor cultivation. When it comes to lighting, this means employing a careful balance of sunlight and supplemental light. It’s revolutionizing the way in which people grow crops outdoors.

To give us some expert insight into supplemental lighting applications for greenhouses, Maximum Yield reached out to Brendan Strath, senior solutions director and grow ninja for Spectrum King LED, a company that makes full-spectrum LED grow lights. Here is what Strath had to say:

The Questions

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

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 combining 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.

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

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 growing. Also, with this method, you can produce quality crops all year round with lower production costs.

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

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 (a.k.a. cold, wind, snow, etc.) are perfect for greenhouses; they offer environmental protections for crops while utilizing sunlight. Grows in those 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.

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?

I couldn’t agree more with that statement. Whether it’s medical crops 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 bonus of supplemental lighting truly diversifies horticultural applications outdoors. Plus, as Strath mentioned, this form of growing is also economically viable and more environmentally friendly. With this sort of best practice, technological advancements have allowed greenhouse growers to devise cultivation methods that can realistically sustain the industry well into the future. Finally, novice and expert growers alike can use supplemental lighting to produce fresh medicines and crops all year round.