Sometimes lighting in greenhouses is needed if less than optimal sunlight is being achieved. The lighting controls can substitute for the sun’s many spectrums needed by plants to produce chlorophyll and grow.
Fluorescent bulbs are inexpensive and effective. The cool bulbs emit light in the blue spectrum; which is conducive to vegetative growth. The warm bulbs emit red light to aid in plants’ flowering and fruiting. The disadvantage of fluorescent lighting controls is the lights themselves don’t output much light so the lights must be two inches away from the plants.
High intensity discharge (HID) lamps are great for medium to large greenhouses. They output more light per cubic feet so they are very effective. Metal halide HID lights emit the blue spectrum needed and is close to natural sunlight. High pressure sodium HID’s supply light in the red spectrums but are not as comfortable to the eye.
Incandescent bulbs burn too hot and don’t work very well at all. For best results in greenhouse lighting control, HID lamps are worth the money.
