For years, commercial greenhouse growers have used supplemental lighting to help boost greenhouse production when the weather won’t seem to cooperate, as well as creating a more uniform product throughout the greenhouse. It began with fluorescent and high-pressure sodium (HPS) lighting, which fed the plants well but at a rather high electricity cost. Once LEDs (light emitting diodes) came out, growers began looking toward the new low energy option. However, like most new technologies, LEDs came with a much higher price tag than conventional lighting.
This year at Cultivate’22, a panel of speakers including Ron Sant (operator at George Sant & Sons Greenhouses), Aren Phillips (lead grower at Walters Gardens Inc.), Roberto Lopez (associate professor at Michigan State University) and Marc van Iersel (Vincent J. Dooley Professor of horticulture at the University of Georgia) gave a lecture on their findings of LED supplemental lighting and the benefits of LEDs in a greenhouse setting.
“I’m not saying LEDs are better than other lights, but they are cheaper to run,” pointed out van lersel. “If you live in an area where electricity costs are higher, LEDs make more and more sense.”
Is the savings worth the switch?
When looking at new installs, most growers look at the price tag on the lights and installation costs. However, the upfront cost of supplemental lighting is just one facet of what you will pay over the life of the system. Additional costs incurred will include electricity usage, bulb replacement and labor. LEDs have an average lifespan between 40,000 and 50,000 hours while HPS has an average lifespan between 20,000 and 30,000 hours.
For most new installs, LEDs make more sense because of the lower energy cost and reduced replacement costs over the years which will save your business money in the long run. However, looking further into the use of LEDs, growers have found additional benefits aside from the direct energy savings.
After using LEDs, Sant noted a better quality in his plants grown under the lighting systems, finding that his seedings were more consistent. “We found better uniformity across the board which resulted in me having less throwaways,” Sant said. This uniformity and consistency reduces labor needs for handling trays, transplant loss and general plant management such as reduced need for plant growth regulators, saving in chemical costs as well.
“We found it easier to sort hosts by color when switching from HPS to LED,” said Phillips. “The LEDs gave truer leaf colors as well as improved root growth and cut down on crop time.”
What to consider when looking at LEDs:
- The cost of the system
- The cost of electricity in your area
- Rebates and incentives from local, state or federal government
- Anticipated maintenance and working lifetime of bulbs
While a red-blue spectrum is good for plants and has been shown to give good growth while using less energy, some employees don’t like working in the spectrum because it can cause strain on the eyes after prolonged exposure.
“Pick the right spectrum and size for your operation. If you only use one-third of the lights you install, then they are three times as expensive,” pointed out Phillips.
Whether you decide to use LEDs, HPS, fluorescent or any other lighting system, be sure to do your homework and find what makes the most sense for your growing operation. Check for all rebates or incentives, determine the total cost and figure out what your ROI will be for implementing supplemental lighting in your greenhouse.
For more information on what supplemental lighting your greenhouse will need, visit hortlamp.org, which offers a lighting cost calculator to determine how much lighting you will need and then how much it will cost.
by Michael Wren