There are a range of bulb types that can be used as grow lights, such as fluorescents, high intensity discharge lamps, and LEDs. The most widely used lights are HIDs and fluorescents. Professional growers typically use HPS and MH HID lights, but fluorescents are quickly replacing metal halides due to their efficiency.
High-intensity discharge lamps (HID lamps) produce light from an electric arc between electrodes mounted inside and on opposite ends of a translucent silica or aluminum oxide arc tube.
High Pressure Sodium (HPS Lamps) are a type of HID lamp and are primarily used with flowering or fruiting plants. HPS lamps are manufactured primarily in the red spectrum to mimic the late summer and early fall sun.
Metal Halide Bulbs (MH Bulbs) are also a type of HID lamp and are primarily used with leafy greens, micro greens, and plants that are in the vegetative growth phase. MH bulbs are produced primarily in the blue spectrum to mimic the spring and early summer sun.
Most HID lights have a lifespan of approximately 2,000 hours. HID lights are more efficient when allowed to warm up; turning a HID light on and off frequently will reduce its lifespan.
Fluorescent lights are available across the blue and red light spectrums, just like HID lamps. Today’s fluorescents are most often used for leafy greens, micro greens, and starting seeds.
High-output fluorescent (HO) lights, commonly referred to as T5’s, produce twice as much light as a standard fluorescent light. A standard fluorescent light produces twice a much light as an incandescent light per watt consumed. Typical lifespan of a high-output fluorescent is 10,000 hours.
Compared to other types of grow lights, such as HID’s and Fluorescent’s LEDs are becoming very economical as they consume significantly less power, and produce almost no heat, therefore enabling them to be placed much closer to the canopy of plants. The spectrum of light emitted by LED’s can be much more fine tuned than with LED’s or Fluorescents. If a LED fixture is illuminated for 12 hours a day it will likely last for 15 years before it needs to be replaced.