How do LED grow lights work?

LED grow lights are popular alternatives to conventional lights because they use far less energy to produce an equivalent amount of light. However, few people understand how LED grow lights work.


How LED Grow Lights Work

Most LEDs or light emitting diodes rely on a semiconductor (or diode) and electroluminescence to generate light. There are two different layers of semiconductor material inside the P-N junction diode. When a voltage is applied, current flows through the materials, creating light via electroluminescence. LED grow lights are often dimmable, because you can still generate light though half as much power is flowing through the semiconductors. However, there is a minimum Wattage that must flow through the leads for them to recombine within the device, releasing light in the process.

LED grow lights can be engineered to product a specific wavelength of light like red spectrum or blue spectrum light. LEDs can be made to put out only ultraviolet light, though this is rare. White or broad spectrum LED light can include red wavelengths, blue wavelengths, UV light and other wavelengths.

Some broad spectrum LED grow lamps actually contain a mix of LED lights, some blue lights, some red lights and a few white lights. In these cases, the owner can switch between predominately red light, blue light or broad spectrum light as required by the plant.

However, there will not be as much light generated as if all of the LED chips were white broad spectrum lights and running at the same time. The classic pink or purple glow in many indoor greenhouses is because there is a predominantly red light being generated with a lesser fraction of blue light being emitted.


LED grow lights, unlike fluorescent lights, don’t require a ballast. This allows them to be plugged directly into a standard light socket.

Depending on the design, more than one LED grow light can be connected in series and draw power from the same power source. In more advanced LED grow lights, there are reflectors behind the bulb to focus more light downward and improve efficiency.

How a LED Grow Light Works Relative to Traditional Alternatives

We’ve answered “how do led grow lights works”. But how do they work relative to traditional grow lamps? High intensity discharge grow lights are the original default choice for grow lamps. These grow lights take a tub filled with gas and metal salts. When an electrical current is sent through the lamp, the molecules are excited, and this generates light.

In the LED grow lamp, the same result is achieved by running power through semiconductor chips. If you drop the LED grow light, there are no toxic heavy metals to escape, and the LED panels tend to be more durable than conventional glass light bulbs. LED grow lights don’t generate as much heat as traditional lamps, though larger ones do need fans to stay cool.

Why Do Some People Think LED Grow Lights Don’t Work?

A common mistake with LED grow lights is setting them up as a distant lamp and expecting them to replace natural sunlight. If you are using LED grow lights as a supplement for natural light, you could see more growth of a windowsill garden or a healthier indoor house plant.

You need very intense LED grow lights to mimic the natural bright sunlight sun-loving plants require. It is actually hard to mimic this with LEDs, though LED grow lights are sufficient to raise leafy vegetables like sprouts and

If you don’t run the lights long enough, the plants won’t grow as much as desired. For example, the fast production of lettuce in just three to four weeks, assuming it has 16-18 hours of mostly red light and all the nutrients it needs. If someone only runs the LED grow lights in the evening when they get home from work, the plants simply don’t get enough light to grow as desired or outright die for lack of light.

The cooler nature of LED grow lights means you can put them closer to plants than conventional grow lamps, though some LED grow lights have infrared bulbs to help warm up your grow tent. You have to pay attention to the data provided on light intensity versus distance. Hang up LED grow lights as far up as your conventional grow lights, and the plants will get a fraction of the lumens you wanted them to get.