Photo courtesy of Hawthorne Gardening Co.

Greenhouse Management: How does the ROI for HPS lighting compare to other options?

Mike Anderson: The only competition for HPS is LED. LED is still four to six times the initial investment and can’t have lower lifetime cost. Yes, LED chips last a long time, but the drivers do not. Most likely, the LED unit will not be repaired, it will have to be replaced when the driver fails. LED is becoming interesting when there is government subsidy to offset the higher initial costs, but after the subsidy, it will be expensive to replace. LED is useful where there are temperature limitations in the growing space or where there is limitation on power availability. When calculating ROI in a normal operation, HPS will always have more advantages than LED. In the recent past (one to two years ago), the real output of the LED fixtures was 2.1 - 2.3 umol (micro moles) per watt. At these efficiency levels, LED systems needed to consume nearly the same or slightly more power than HPS. Recently, we see fixtures with 2.7 or more micro moles per watt, but still the ROI is less favorable when compared with HPS.

GM: What are the benefits of using HPS lighting, even as other options have become more popular?

MA: HPS is one solution but may not be the best solution depending on the particular needs of the grower. HPS is a proven and reliable technology which can be used in all kinds of cultivation, from flowers and plants to vegetables and fruits. HPS provides the best return on investment, lowest initial and lifetime costs, and is a mature and proven technology that is easy to maintain. We have decades of lighting design experience utilizing world-class HPS reflectors to create the best light uniformity in the market for greenhouse or indoor facilities.

GM: Have HPS lights become more efficient in recent years? If so, what does that mean for growers?

MA: Growers continue to ask for more light per fixture to maximize plant growth at lower cost. A rule of thumb is that increasing the amount of light available to the plants by 1% (measured as PAR) correlates directly with a 1% increase in plant production. We continue to work with our vendors to drive efficiency and lower cost for the grower. Lamp cost is relatively low, so the next large gain may be to increase light output even if it lowers lamp life so that growers benefit from increased plant yields.

GM: How can Hawthorne help growers find the right lights for their greenhouses?

MA: With Gavita, a division of Hawthorne Gardening Company, we are the global market leader in the horticultural light business and we know what light can do for each specific crop. Hawthorne has a technical services department that was created to work with new and existing growers. We meet with growers to design the best solution for each growing situation, taking all growing, environment and legislative aspects into consideration. In this way, we can create a total light calculation, an ROI and offer the right solution for every grower around the globe. Our broad product portfolio makes it possible to select the right fixture for the application.

Sven Springintveld, general manager for Gavita International b.v., and Arjan Pauw, horticulture international sales director Horticulture for Gavita International b.v., contributed to these answers.