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How Far Should LED Grow Lights Be From Plants?

led grow light distance 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.

The most technologically advanced LED lights have completely revolutionized indoor and greenhouse growing. Lights like the SolarSystem® series from California Lightworks are helping growers achieve their highest and most potent yields yet. Between the high-intensity output and variable spectrum control, these lights are the best option for mimicking sunlight and manipulating your product. Plus—as you’ve undoubtedly heard by now—LED lights to accomplish all this while using limited energy and emitting very little heat.

However, in order to use all these benefits to their fullest potential, you must determine the optimum placement in relation to your canopy. Unfortunately, there is no set standard. All LED lights are a little different, which is why the absolute best advice we can offer is to consult with the manufacturer of your specific light.

Beyond that, here are a few insights and tips that can help you make the wisest choices for your plants.

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.

Again, these are general guidelines. Discuss the ideal distances with your manufacturer and keep an eye on your plants for signs that you’re overloading them. If your plants are getting too much light intensity, they’ll let you know. Here’s how:

How to Recognize Light Burn On Your Plants

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.

Specific Suggestions for California Lightworks LED Grow Lights

SolarSystem® Series

The SolarSystem series features narrow light angles and higher power so these lights are designed to hang higher than other LEDs. A digital spectrum controller is available which allows you to dim the lights rather than raising or lowering them. This is the best option and avoids constant raising and lowering of the lights.

If you do not use the controller, you can adjust the intensity by raising and lowering the lights:

Propagation – spouts and clones – up to 48 inches

Early Veg – 36 to 48 inches

Veg – 36 inches

Pre-flower – 24 – 36 inches – lower the lights gradually

Flower – 24 – 36 inches depending on the canopy – maximum intensity evenly spread over the canopy

SolarXtreme® Series

The SolarXtreme series features wide angle COB LEDs. These can be hung much closer to the plants and are especially well suited to tent grows where there are highly reflective walls close to the plants.

Propagation – sprouts and clones – 24 to 36 inches

Early Veg – 24 – 36 inches

Veg – 24 – 36 inches

Pre-flower – 24 inches

Flower – 18 to 24 inches

*In all cases, adjust the light intensity to best suit your plants – they will let you know when they are happy!

The Bottom Line

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.

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 light system for your plants.

 

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One Comment

  1. Thomas Atwood Reply

    I leave my solar system 1100s at max height and use my system control to lower or increase intensity using a par meter, the plants grow to the light and I never move them, my results are incredible I would recommend this system to anyone and everyone who is serious about growing this is not a toy it’s an awesome tool.

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