Light emitting diode (LED) grow lights are a form of technology often used to provide plants and flowers with sufficient light to grow in greenhouses and indoors. It is an alternative to high intensity discharge (HID) lighting and metal halide (MH) lighting, which often use up to 75 percent more power and produce more heat than LED grow lights. Whether for commercial or non-commercial use, LED grow lights usually offer energy savings and are easy to install. They can also be combined with solar and wind technologies to maximize savings on electricity bills.
Manufacturers of LED grow lights often measure the brightness in lumens or lux. These measurements refer to how bright the room appears when the LED light is turned on. This is not indicative of how well plants will grow, however, because it is not based on photosynthetically active radiation (PAR), which is the part of the spectrum plants use. The micro Einstein measurement is often a better way to measure the ability of a lamp to grow plants. The human eye cannot see more 60 percent of the light that LED grow lights emit, and therefore lumens and lux measurements can often be misleading as to the amount of light the plants will absorb.
LED grow lights are often comprised of a single light bar with several LED bulbs installed. Each light bar is mounted directly above the plants or flowers, usually no closer than 12 inches (30.48 cm). Depending on how many plants there are, it often takes several light bars to help the plants grow. It is important not to look directly at LED lights for long periods, because it may harm the eyes.
The main benefit to using LED grow lights is the ability to deliver high intensity light in indoor spaces. This light can extend the growing season by allowing plants to be grown indoors prior to transplanting outside, or even as an alternative to gardening outdoors. Grow lights are also great for plants that don't require heat to grow, because the heat output is low.
For many users, LED lights are preferred over HID lights for several reasons. The ballasts of HID lights are often noisy, while most LED lights are nearly noiseless. The lifespan of LED grow lights is typically about 50,000 hours; the lifespan of HID lights varies by type, but is typically less than half that of LEDs. LED grow lights are directional, while HID lights need reflectors to direct the light.