LEDs Comparable To High Pressure Sodium Lamps For Cutting Propagation, Researcher Says, At Cultivate’14

By Janeen Wright|August 12, 2014

LEDs or light-emitting diodes have made inroads into the young plant market as a viable alternative to conventional lighting methods for liner and plug production. With such a huge investment riding on the choice of lighting, growers sometimes wonder if there is an advantage to making a switch from conventional methods like high-pressure sodium (HPS) lamps to LEDs for supplemental or sole-source lighting.

Christopher Currey, department of horticulture professor at Iowa State University, answered this question and more at a recent Cultivate’14 presentation on the future of young plant production with LEDs. Currey shared findings from his research work, done in conjunction with Robert Lopez, Purdue University, comparing supplemental and sole-source LED lighting to HPS lighting.

Currey said their research shows that LEDs are comparable to HPS for cutting propagation, and plug quality is similar to or better for seedlings grown under LED treatments when compared to those grown under HPS lamps. LEDs are also suitable for providing supplemental light for plug production, with some benefits over HPS lamps such as more compact plugs and flowering plants under blue light.

When high electricity costs or limited energy availability is a concern, LEDs might be the better option for photosynthetic lighting, Currey said. Other situations might be year-round use in an enclosed environment or the need to position lighting close to the crop.

However, growers looking to make a switch to LEDs need to look closely at how they are cooled (actively or passively), Currey said, because passively cooled lights consume less energy. The design of the light also affects energy consumption and shading. Another consideration, he says, is crops growing under HPS lamps can be 2 to 4 degrees Fahrenheit warmer than their LED counterparts are because LEDs don’t emit heat.