According to the associates at Oregon State University Extension Service, red light and blue light from the visible light spectrum are the most beneficial colors of light for plants. Red light encourages flowering in plants, while blue light encourages vegetative growth in plants.
Most stores that specialize in grow lights carry LED set-ups that feature red and blue LEDs.
LED grow lights have generous light outputs for the small amount of power they require to operate. Unlike most other types of grow lights, including metal halide lights and high-pressure sodium lights, little energy taken in by LEDs is given off in the form of heat.
According to LED Grow Master.com, most grow lights contain traces of toxic elemental mercury. LEDs, on the other hand, contain absolutely no mercury. A 250-watt metal halide bulb can contain 38 mg of elemental mercury. A high-pressure sodium bulb of the same wattage can contain around 15 mg of elemental mercury.
According to EarthEasy.com, LEDs are more durable than most other types of light bulbs. They attribute this to the fact that LEDs contain no filaments, which are traditionally very delicate and prone to breaking if jarred or mishandled.