If you’re trying to figure out the perfect distance between your plants and the LED lights nourishing them, you’re already ahead of the game. Too many growers overlook light placement or decide to wing it. At worst, the result is a struggling, unhealthy crop. At best, they don’t get the full benefits of choosing LED lights to begin with.
Lots more growers are starting to use grow lights for indoor plants, especially LED grow lights, but there's a lot of confusion about exactly how to use them. One of the most common questions about using LED grow lights is how far they should be from plants.
In general, LED grow lights should be 12-30 inches from the tops of plants. As plants grow, you'll adjust your lights to maintain a consistent distance from the plants. However, the distance will vary depending on the wattage of your lights, the type of plant, and the amount of ambient light.
Once again, it is important to understand that there is no universal rule for how far to place LED lights from plants in each phase of growth. Different manufacturers construct their LED lights in different ways. There are multiple details to take into consideration, such as the power and angle of individual LED diodes within a fixture and the use of lenses to reflect light downwards. The best way to get that perfect distance between the light and your canopy is to consult with the manufacturer. Also, you need to consider different watts should place in different height, 480W LED grow light is different other watts lights.
The second thing to keep in mind is that the correct LED light placement changes for each stage of growth. If your LED is dimmable, you can use dimming to adjust the intensity of the light on the plant surface. If your LED is not dimmable, your only option is to change the hanging height. These examples aren’t hard-and-fast rules, so don’t follow them without the blessing of your light’s manufacturer. But just to give you a ballpark sense of what LED light placement generally looks like throughout the growth cycle:
Seedlings need the least intensity and most distance between the canopy and the lights. You may have the instinct to blast these little guys with high-intensity light to promote fast growth. The truth is, they’re young, vulnerable, and likelier to thrive with a gentler approach.
In the vegetative stage, you want to get your LED lights closer to your plants. In general, plants in veg only need about half the light that they need in bloom. It follows that you could have up to twice the hanging height that you use in bloom.
It’s in the flowering stage that you really need the highest intensity. It is important to build in a “hardening off” phase as you move from veg to bloom. Slowly increase the intensity or lower the hanging height until you reach the manufacturers recommended height in bloom.
The need for hanging different lights at varying heights is primarily due to the spectrum of the light and its intensities along with heat emitting factors so they need to adjust at the height that is the most suitable for growing where your plants are neither underexposed to light nor overexposed as in both cases their growth will be retarded. Hanging them too close to the canopy will burn them will hanging too far will not meet their heat intensity requirements they need to complete their physical processes like photosynthesis and mass assimilation. Most of the manufacturers include a complete guideline regarding this that how for their lights need to be hung for a different type of plants along with the wavelength and intensities, they produce.
The LED grow light height in case of 1000 W is suggested 36-42 inches for the vegetative stages while for blooms it can be kept at 18-24 inches from the plant’s canopy. Similarly, The LED grow light height in case of 600W LED grow light is suggested 32-36 inches for the vegetative stages while for blooms it can be kept at 18-22 inches above the plant’s canopy and for 300 Watts you can keep 16-30 inches in the vegetative stages and 16 to 18 inches for flowering or blooming period.
Because LED lights give off so little heat, you don’t run much risk of causing heat damage by placing your fixture too close to the canopy. What you do risk is light burn. Unfortunately, the light burn is easily mistaken for nitrogen deficiency, and many growers wind up misdiagnosing their grow and addressing the wrong problem.
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.
If it sounds like your plant has a light burn, it’s time to reevaluate the placement of your LED lights.
Final thoughts
Your best bet for getting the exact perfect height is to consult with the manufacturer of your specific LED light. If you’re still on the hunt for an LED light, include customer service as a consideration when weighing your options. Choose an LED light manufacturer that offers easy access to expert insight.
At California Lightworks, we have U.S. based customer support and a great reputation for helping growers set up their best-ever grow operation with cutting-edge spectrum variable LED lights. If we can do the same for you, drop us a line. We’re always here to answer your questions and help you create the best full spectrum LED grow light system for your plants.