How High To Hang Grow Lights Above Plants – Based On Science!

Lots more growers are starting to use grow lights, 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.

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.

LED Grow Light Placement
If you do not have reflective walls, the inverse square law is very important, and you should never raise the lights higher than the manufacturer’s recommendations. Moving the lights too high in this case greatly reduces light intensity and yield.

REFLECTIVE WALLS
While the inverse square law applies to any light – these changes drastically when you use reflective walls. Reflective walls bounce the light back to your plants and greatly reduce the light loss from moving the lights higher. So, when using reflective walls in a grow room or grow tent, it is possible to place the lights much higher without losing a large percentage of the light.

If you have efficient reflective walls – going higher is normally better than lower regardless of which LEDs you are using. With reflective walls, the light bounces from many different angles into the plant and you will get move even yields and deeper penetration into the canopy.

The distance between your LED lights and your plants is, in fact, an exact science. Seemingly minor adjustments make a huge difference when it comes to giving your plants the kind of light intensity that makes them flourish, without giving them so much that they burn and wither.

OVERLAPPING LIGHTS
In larger grows where there are many lights in the same room along with reflective walls, it is often more effective to puts the lights higher so that the is overlap between many lights. This means that each plant will get light from many angles and this will promote much better penetration into the canopy and better overall yield.

For professional installations, California Lightworks can prepare a computerized light plan which can present the best light orientation in any environment.

Understanding this, the inevitable question is: What is that exact right placement?

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 help your plant avoid be hurt

LED lights tend to produce less heat than older technology, and their light intensity is relatively low. This has lead to the conclusion that you can put plants as close to the lights as you want and you won’t burn them.

The reality is that modern LED grow lights can produce a very high level of light and it can cause photo-bleaching and burn leaves. This depends very much on the plant, but a PPFD of 800 is enough to damage some plants.

If you notice your plants wilting, looking burnt, the leaves looking dry or discolored, then move the lights further away. It's basically like looking at your plants to make sure you're not getting them sunburnt.

Typically, when plants start flowering & producing fruit, you'll need to move the LED light closer to the plant so it'll have more light available for photosynthesis & producing flowers & fruit.

If your LED lights are too close to your plant, the plant will begin to bleach and develop yellow spots. Since LED lights do not produce as much heat as other types of grow lights they do not burn plants as much. However, you should still be cautious if the plant presents signs that it is being burned.

Best grow light 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 close-proximity, controlled environment agriculture, and multi-tier vertical farming environments. An average — not max — PPFD above 1,020 makes SPYDRx PLUS the perfect choice for high-DLI crops from veg to bloom when paired with a 0-10V dimmer or adjusted mounting height for desired PPFD.

Current lead time is projected to be 30 days from the time payment is received. For orders over 100 units, please contact us at 512-212-4544.

Recommended mounting height 6” from top of canopy for optimal light uniformity, penetration and flux density above a 4’x4’ canopy.

Suitable for operation in still air ambient temperatures from -40°C (-40°F) to 35°C (95°F) when suspended and up to 30°C (86°F) when surface mounted. Operating temperature ranges between 25°C (77°F) to 30°C (86°F) above ambient.

LUXX Lighting 645w LED Pro

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.