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How Do Plant Grow Lights Work?

Importance of Light

To plants and to nearly everything else on the planet, light is energy. Plants use this energy to grow and thrive through a process known as photosynthesis. However, indoor plants, or plants in a greenhouse, may not receive all of the light they need in order to grow properly. Therefore, plant grow lights are a tool gardeners can use to supplement the sun's light when the sun is not enough.

Types of Light

In order for plants to thrive, the first thing a grow light must do is provide the light in a way that plants can take full advantage of it. Therefore, it's important for a gardener to understand the different grow lights, what they provide and how they provide it in order to truly be effective in choosing the right one.

Full-spectrum lights, such as fluorescent lights and LEDs, generally try to imitate the sun's rays precisely. Some of the light on that spectrum may or may not be useful to plants, but it is a safe, general use light. Violet and blue light, such as that provided by metal halide lights, produce a blue and violet light that promotes vegetative growth. At the other end of the spectrum is the red light, a specialty of high-pressure sodium lights, which promotes flower growth.


Unlike the sun, plant lights work by giving the gardener the chance to have the greatest amount of control over plants. Those who want them to flower at a certain time of year may switch to a different type of light, or give them more light. If vegetative growth is important, that can also be accomplished with a certain kind of light. In all, the options available via artificial light are much more than would ever be available with only natural light. You are the one responsible for making those decisions. Generally speaking, plants need at least 10 to 12 hours of light a day.


Once the selection of the light and timing are considered, the next important part of the process in making the lights work most effectively is their placement. Some lights include stands. If not, stands can be bought. This is another important way of ensuring the light gets to where it's needed most. Stands offer a convenient way to position your grow lights and help avoid plants getting too close to the light source. Some light sources can become quite hot, causing the plant's vegetation to actually become scorched.


Placement is important but may not be enough. Depending on the type of light product you select, grow lights may also provide reflectors. These work by directing the light in a certain direction to give plants the maximum benefit of all the light. As with any lighting product, it's nearly impossible to keep some of the light from being lost, but reflectors offer a great way to get as much light as possible to where it's most needed.

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