HID or High Intensity Discharge Lamps are the top choice among growers. Types of HID lamps include high pressure sodium (HPS) and metal halide (MH) bulbs. Today, they are a top choice among growers because they have a very high light output and are 4 to 8 times more efficient than incandescent lamps.
HID lamps produce a large amount of heat, so extra ventilation and proper reflector height should be taken into consideration when planning a grow enclosure and hanging your lights. Ideally, you should hang your lights about 2 feet from the top of your plants. A good way to check the height of your lights is to hold your hand just above the plant – If the heat from the light is too hot for your hand, then its too hot for your plant!
