LED lights are very efficient and economical for growing plants indoors. New technology combined with the increased demand for energy-efficient lights is lowering the production costs of LEDs making them a feasible source of light for many uses, including grow lights. They can be used every day, all year long and only cost pennies in electricity usage.
LED lights are actually not bulbs at all, but rather light-emitting diodes. They are part of an electrical circuit where the current passes through a diode composed of gallium nitride crystals that radiate light waves immediately when charged. For this reason, there is almost no heat given off from this type of light. There are no removable bulbs; instead the diode is actually soldered in place. LED grow lights are a circuit of many separate diodes. They can be engineered to fit in a standard light bulb socket, as well as in a fluorescent light fixture.
You can eliminate the wasted light normally given off by halide, fluorescent , high pressure sodium and incandescent light bulbs when using the LED lights, which give off just the red and blue light wavelengths. Plants don't need the whole spectrum of light waves that are visible to the human eye. They can absorb all the light they need for photosynthesis from the waves emitted from the red and blue LED diode.
LED lights often have a lifespan of seven to 10 years and consume very little energy, many as little as two watts. They will easily outlast the fluorescent, the incandescent, the high pressure sodium and the halide grow lights while at the same time using far less energy, resulting in an overall savings much higher than the initial cost.
Because LED grow lights are a combination of the red and blue wavelengths, their usage needs to correspond to the needs of the plants you are growing. For instance, the red wavelengths are great for leafy growth while the blue are better for fruit producing plants. A light that emits both the red and blue diodes are recommended as a general all-purpose grow light, although you can get grow lights with just the blue light diodes or just the red light diodes.
Place the grow lights anywhere from three to 12 inches away from the tops of the plants. The light is already directional so you don't have to use any reflectors and since the diodes are cool to the touch, you will not have to worry about damaging the plant with hot lights. Keep the lights on for the amount of daylight time the plant needs, typically from six to 12 hours.