How High To Hang Grow Lights Above Plants – Based On Science!
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.
How Far To Place LED Lights From Plants In Each Stage Of Growth
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.
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:
LED Light Placement For Seedling Stage
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.
Vegetative Stage
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.
Flowering Stage
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.
Best height of each stage
- Early Veg – 24 – 36 inches
- Veg – 24 – 36 inches
- Pre-flower – 24 inches
- Flower – 18 to 24 inches
Best height of different watts
Wattage Distance from top of plant (inches)
200-399 12-20"
600-799 20-27"
600-799 30-38"
800-999 32-42"
1,000+ 36-46"
Best LED grow lights recommend for you
ThinkGrow Model-H 630W Horticulture LED Grow Light
The Model-H is a high performance LED grow light for the horticulture cultivation. It is designed specifically for high PPFD cultivation practices in vertical farming. Full spectrum design with spectral tuning capabilities cover each critical phase of growth from vegetative to flowering.
ThinkGrow is brought to you by the same company making TrolMaster controls -- currently one of the most sophisticated digital environmental controls on the market. ThinkGrow LED lights are also fully compatible with TrolMaster controllers with up to 256 lights being able to be controlled per digital channel.
Fluence SPYDRx PLUS LED Grow Light
SPYDRx PLUS is designed for full-cycle commercial cannabis cultivation with the power to scale from vegetative growth to bloom. For optimal results, we recommend CO2 supplementation between 800-1400 ppm due to high PPFD levels. Also designed to cover a 4’x4’ area at only 6 inches above canopy, SPYDRx PLUS delivers an average of 1030 µmol/m2/s of light over your crop with unparalleled uniformity.
Like the entire line of Luxx products, the new 645 LED Pro was built on the principle of design, test & repeat. It has been developed by assessing SMD (Surface Mount Device) chips and drivers from leading manufacturers in controlled test applications and cultivation facilities for 3+ years.
The LUXX 645 LED PRO is made up of Samsung horticulture whites and Osram reds. The respective companies lead the field in LED R&D, delivering high efficiency, reliability & diode performance. The LUXX 645 LED PRO deploys a lens angle of 120 degrees, from a 6 bar design, with a total of 2,226 diodes.
Final thoughts
The intensity or distance between your plants and LED lights is crucial to the health of your grow. Run the lights too high power or place the lights too close, and you can damage the plant. Underpower or hang them too high, and you miss out on the highest possible yields and potency.
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.
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