LED greenhouse lighting is poised on the hockey stick of the adoption curve, saving electricity while potentially improving the world food supply. The past year has seen production-scale deployment emerge out of years of trial grower installations. LEDs have a unique efficacy advantage in horticulture. Plants appear green because they absorb red and blue, the band gap energy of the two primary photosynthetic reactions. With LED lighting, the color of the light can be tuned to “horticultural red” (660 nano-meters) — deeper than the standard traffic light or brake light.