LED grow lights do produce less heat than other grow lights but that doesn't mean it won't cause any heat problems. LED grow lights can give your leaves light damage. This is known as light burn.
Can LED Grow Lights Burn Plants?
Yes, LED grow lights can light burn you're plants if you place them to close to you're plant. The leaves will first turn yellow, then brown, and will eventually fall off. Always keep the grow light at least 12 inches away from you're plants to avoid this.
How To Know If You're Plant Has Light Burn
If your plants have light damage, you’ll see symptoms such as:
Leaves point upwards.
Bleaching, which takes the form of white or yellow discoloration, typically on the leaves closest to the light.
Veins remain green even as the rest of the leaves turn yellow.
A nitrogen deficiency has similar characteristics, but there are a few notable differences.
A plant with a nitrogen deficiency also develops yellow patches, but the damage starts from the bottom of the plant and works its way up, while light burn begins at the top, closest to the lights.
In the case of a nitrogen deficiency, leaves wilt. In the case of a light burn, leaves turn upward and sometimes even become brittle.
The leaves of a nitrogen deficient plant fall off on their own. This does not happen to plants suffering from a light burn.
Your plants can only withstand a certain amount of light. After a certain point, your plants will start turning yellow or otherwise exhibit signs of stress on the leaves near the sources of light and/or heat.
If the LED grow lights are only slightly too close, maybe just an inch or a few centimeters, the yellowing from light burn may happen slowly over the course of days (or even weeks!) because leaves are dying early instead of immediately. Because of that, light burn may first appear on somewhat older leaves, which can be confusing and make it hard to diagnose.
If you see light bleaching and unhealthy discoloration only on the parts of the plant directly under your LED grow light, or only on older leaves that are exposed to the light, it often means it’s too bright for your plants and you should move your grow lights further away!
How Far LED Grow Lights Should Be From Plants
If it sounds like your plant has light burn, it’s time to reevaluate the placement of your LED lights. If you hang your LEDs too far away, there’s a good chance your plants will over-stretch in an effort to reach closer to the light.
If, on the other hand, you place your LED grow light too close to your plants, this can stress the plants more, causing burning and bleaching of the leaves.
So, what is the ideal distance between your LED grow lights and your plant canopy? Well every LED Grow Light comes with an instruction manual which should inform you on how far it should be from you're plants. If you can’t find it there, check out the manufacturer’s website.
When adjusting the height of your LEDs for peak performance, keep an eye out for any oddities. Dry, curled, brown, or bleached leaves signal too much light, calling for your LEDs to be raised higher. Most LED Grow Lights should be at least 12 inches away from you're plants. This will ensure you're plants will be safe from getting light burn and produce the best results.
Not all grow lights have the same heat, and usually, it’s the heat that burns plants. Some grow lights, like HID lights, have bulbs that can get really hot and can basically burn your plants (especially if they’re too close to the plants.)
RELATED POST: LED Grow Lights Vs HID Lights
Of all the mentioned grow light types, LED grow lights are the best option. Even though LED grow lights also produce heat, they deal with the heat more effectively and you can put your plants much closer to LED grow lights that other types of lighting.