The development of grow lights comes on the back of detailed scientific research into how plants absorb light and use this in their process of photosynthesis. It is now understood that certain wave lengths of light are more useful for plants than others. Four maximum chlorophyll absorption points have been identified, two in the red/orange and two in the blue/purple sections of the electromagnetic spectrum. Red/orange wavelengths promote growth while blue/purple encourage flowering and compact growth.
The three main grow light types on the market are LED grow lights for sale, HID grow lights and Fluorescent lights. When comparing all the options on the market LED grow lights in particular are gaining in popularity as they produce a light that directly mimics the most useful blue and red wavelengths. In addition they have a lower heat signature than HID and fluorescent lights which cuts down on dehydration and scorching risk.
High Intensity Grow lights are also widely used in grow light gardening, in particular metal halide. metal vapor, and high pressure sodium lights. But while they produce a great deal of light at high intensity not all of this can be absorbed by plants making them less efficient overall. They also emit a high amount of heat with larger systems requiring air conditioning and high voltage ballasts.
Fluorescent light are another option for grow light gardeners to consider. These typically have a lower up front cost and are very energy efficient. Some of the basic models do not emit a very dispersed light and reflectors are normally needed to direct the light towards the plants (and away from the ceiling). Fluorescent bulbs are often used by amateur gardeners on seedlings to encourage quick growth before they are transplanted to more permanent positions. They have a low heat signature and expensive accessories are not needed as part of the installation.