Keeping an Optimal Distance between LED Grow Lights and Plants

Simply setting up your indoor grow room with a lighting system will not ensure that you will get the optimal results possible. You will need to push the limits, but mainly you need to adjust the optimal height of LED grow light from your plant during the entire grow to maximize results.

It might seem like an easy task, but growing cannabis is a difficult process. When plants are taken indoors under an optimized lighting system, the distance of the lights from cannabis is often overlooked. Yet this is one important factor that separates pros from novices. The right grow light at the right distance from the plants can make all the difference to the crops.

LED Grow Lights and Plants

The question here is: “if plants are getting good light coverage, shouldn’t that be enough?” Certainly, light coverage is necessary for the plants as you’re using the grow lights instead of natural sunlight. However, in addition to proper coverage you will need to adjust the height of the light from the plant canopy to train your plants to keep growing vertically and/or horizontally. The position of the grow light will determine if your plants will stretch or become bushy.

Closer the Light

The closer the light is to the cannabis plant, the more intensity of light and quicker the growth. Bring your lights too close to the plants and they will experience stunted growth and possible bleaching of leaves. If you see the tips of your leaves bleaching, this means the light is too close and too intense, causing more harm than good. Adjust the light up a few inches and wait a few days to see if the plant is recovering.

Farther the Light

The farther the light, the more the plants will stretch and reach towards the light source. Growth will be slower because there will be less intensity but the plants will grow taller over time instead of denser. The indoor grow lights are subject to the Inverse Square Law. The principle states: the light diminishes exponentially in energy as the distance it travels increases. In simple words, this means that lesser energy will be available for your cannabis with the tradeoff of covering a larger total floor area.


PAR is the measure of the energy given to the plants and stands for photo-synthetically active radiation. Consider this example to understand the importance of optimal distance required for lights when growing indoors. A light that produces a PAR rating of 1000 at a given distance will product a PAR rating of 250 at twice the distance. The goal should not be to maximize the PAR value; but to find the equilibrium point where the plant will grow tall yet be dense enough to produce heavy buds.

The advancement in LED light technology has made it possible for growers to take their growing inside. And completely control their grow environment. There are no set of standards as to how far the lights should be set from the plants; but there are certain factors that can help in weighing and working out the light adjustment process.

The Weighing Factors

The most important factor is providing the right light. Choose a high quality LED grow light that has an optimized diode wavelength blend and ratio. Ensure that your entire canopy is receiving the light and the light coverage is maintained. Once you have met this parameter, the next is optimal light height. Higher wattage lights should be kept at a larger distance to A) avoid stunted growth & leaf bleaching and B) have enough room to spread the light over a large enough area.

Optimal Distance from Cannabis with LEDs

LED grow lighting is the best innovation in light technology which makes indoor growing simple and easy to manage. If you are using LED lighting system, the optimal distances will depend on the wattage of diodes; the lower wattage of the diodes-the closer you can keep to the plants. LED lights with power draws of 400watts or more should be kept at a minimum distance of 2 feet above the plants. LED lights with lower power draw of 100-400watts can be kept closer to the plants, at 1-2 feet from the plants.

Generally, LEDS put out minimal heat so drying leaves and burning plants is not an issue, even with higher wattage lights. The closer the light, the more energy the plant receives. However, if you bring your lights too close to the plants you will do more harm than good and your plants will not be motivated to grow. Balance is the key and finding the right equilibrium point will give the best growth and yield for cannabis plants.

Setting up LEDs

The best method for setting up LEDs for your cannabis is to start them at the manufacturer recommended distance from the top of your plants. And then lower them for coming days of growth process. If during this time period you see the plant leaves bleaching out; raise the light a little bit at a time until you find the equilibrium position. The bleaching has to stop for you to determine the optimal distance of LED grow light form your plant.

Once you have the optimal distance, maintain the distance as the plants grow towards the light source. Raise the light as the plants grow to keep a constant distance between the plants and the lights. Once you start flowering, you can stop raising the LED lights. And let the plants find their own equilibrium distance to their energy (light) source. With LEDs you can make the quality of your growth worth the effort; enjoy the innovation as it leads you to natural and fresh indoor plant harvests.

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