Research Shines Light On Gardening Question

Jun 24, 2014

Though the sun is still the primary source of light for most gardeners, many rely on electric lights some of the time. But varying claims on the efficiency of these lights from different manufacturers has left many growers confused about which products to use, according to Bruce Bugbee.

The efficiency of lights used for growing home gardens and crops has changed in recent years, leaving many to wonder which lamps to use.
The efficiency of lights used for growing home gardens and crops has changed in recent years, leaving many to wonder which lamps to use.
Credit epa.org

Bugbee, a professor in Utah State University’s College of Agriculture and Applied Sciences, along with graduate student Jacob Nelson decided to look into these claims, publishing an article on the topic in the journal PLOS ONE.

They compared 22 different kinds of lights, including  LEDs, fluorescents, ceramic metal halides and high pressure sodium fixtures, the kind of lights used in street lamps.

“The very best technologies were high pressure sodium lights and LEDS are also excellent, except they are really expensive,” Bugbee said.

He said the research showed LEDs cost 5 to 10 times as much money per unit of light compared to the high pressure sodium lights, mostly due to replacement costs.

Coming in last for efficiency were florescent lights, said Bugbee.

Overall, the type of light a grower should use depends on how their greenhouse is set up. Bugbee explained the high pressure sodium lights shine light over a broad area, whereas LEDs are more like tiny, directed spotlights.

“For big growers, I think the high pressure sodium lamps are still the best technology, the LEDs need to come down in price before they are the best technology,” Bugbee said. “But, for home owners it’s a different story.”

He said if home gardeners have a small greenhouse, LEDS can be the best choice.