High pressure sodium (HPS) bulbs mimic the natural sunshine during the Fall season. They are high in the yellow and red regions of the light spectrum, giving off a pink to orange coloring.
HPS lights stimulate flower and fruit production more efficiently than MH, making them an important light source. They are, however, best used in conjunction with metal halide lights to prevent leggy vegetative growth.
They have long life expectancy, lasting up to two years! Several lights? Get bulbs by the case!
Find bulb recycling info at LampRecycle.org.