Marijuana Planting Guide: Why Is Led Light Distance from Plants Important

Like any indoor planting, the LED light distance should be noted for higher yield and for the potency from your plant. This guide answers how far away your LED light should be from your marijuana plant and why this distance is essential.

3 Reasons LED Light Distance Matters

Many people are moving away from the more famous and traditional fluorescent T5s to LEDs (light-emitting diode) not only because they are more cost-effective in terms of power consumption, but also because of these 3 reasons:

Increase Yield

Growing your marijuana plant with LED already generates a higher yield per square meter than other light sources. This is because proper lighting can optimize photosynthesis and in turn, improve flower production and increase your yield number.

But the type of light won’t be enough to increase yield – you have to ensure the distance from the light to your cannabis plant is perfect in every growing stage from germination to seedling, and vegetative to flowering.

Improve Potency

THC (short for tetrahydrocannabinol) is the chemical responsible for most of marijuana’s psychological effects. High THC cannabis is known to treat nausea, arthritis, muscle spasms, multiple sclerosis, and other ailments.

LED grow lighting is able to control or program how the cannabis plant would grow and flower, as well as how much resin it would produce. It is during the flowering stage that improving potency is possible. As such, controlling the distance of the LED lights (as well as the light spectrum) during this phase not only results in an overall higher yield, but also in harvests with the highest THC percent levels (which have a higher market value).

Prevent light burn and nutrient deficiencies

The most apparent reason to be especially careful with the distance of LED lights from your plant is to prevent light burn. Because all parts of a cannabis plant are consumable, you wouldn’t want any leaf, flower or stem going burnt due to them being too close to the light source. It’s a totally preventable problem.

Preventing nutrient deficiency is more challenging. As such, you need to master when to adjust your LED lighting. This way, your cannabis leaves won’t turn yellow and you no longer have to worry about your plant’s photosynthesis rates decreasing at an alarming pace.

Cannabis LED Light Distance by Growing Stage

The problem with LED lights for indoor cannabis growing is that there are so many options. Of course, this is a welcome “problem” for most growers, especially for growers who began years back when not many states legalize it.

The recommended LED light distance from your cannabis plant will depend on the brand and model, but as a guide, you can follow these estimates by growing stage or marijuana plant maturity:

Seedling stage:

Sowing (the part when you place seeds on soil) requires zero to very minimal lights. But once the roots are firmly established on the soil, you’ll need to gradually increase the intensity of your LED lights and lower the distance of your lights to the plants.

Seedlings are like babies, so expect that they are delicate. During this time, cannabis plants don’t need too much LED light intensity. Growers also note that the soil could go dry quickly if you place the lights closer to the grow bed. The general advice is to put the lights around 24 to 36 inches from the topsoil to the light during the seedling phase.

Vegetative stage:

Your cannabis plant would be more established by this stage and wouldn’t mind intense lighting. As you increase light intensity and bring down the lights slightly closer to the plant, you’ll be encouraging their roots to grow healthier and stronger. You can place the LED lights around 20 to 36 inches above your plant during this maturing stage.

Do note that this is also the stage wherein your plant would grow the most, so watch out for signs that might tell you that you’re using too much light (or too little) and adjust the distance as needed.

Flowering stage:

The flowering stage require LED lights to be 16 to 35 inches above the plant. Because your marijuana plant is almost established, it will have bigger leaves and an overall taller appearance.

You need to master adjusting the LED light distance because leaving it too close could cause damage, stunted growth, or even death. Meanwhile, leaving the lights too far from the plant can also cause stunted growth or a lack of nutrients (like yellowish leaves).

If you’re taking care of clones (clippings/cuttings from mature cannabis to grow another smaller plant of the same species), the LED lights should be around 14 to 36 inches above them.

Other factors that would be considered when estimating LED light distance include the power output of your LED lights (wattage), the individual size of each LED bulb, and more.