How Far Should Your LED Light Be From Your Weed Plant? 

 July 7, 2022

By  lightmyleaf

How Far Should Your LED Light Be From Your Weed Plant?


When growing your indoor plants through LED grow lights, you need to maintain the right distance. If you are confused and thinking about what distance we are talking about. This is about the distance that you need to maintain between plants and the grow light hanging above it.

Maintaining the right distance is a tough task that most growers and farmers face. Some growers hang the LED grow lights 30-40 inches above the plants. It affects the growth and results in weak plants. Since the light cannot reach plants effectively, the photosynthesis process doesn’t take place properly.

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If you want your plants to absorb light for efficient growth, you have to keep an ideal distance. In order to make plants absorb the light effectively, some growers hang them too close to the plants. As a matter of fact, this closeness of LED lights will also negatively affect your Plants. This causes the plants to stress out easily.

Hanging too far will throw away the light while hanging too close with damage the plants. So, how should you choose the right length for your plants? This is what you are going to know in this piece of blog. Continue reading to know more about it.

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Leaf Temperature To Note First

To maintain the right distance between hanging LED grow lights and your indoor plants, you must consider a few factors. According to experts, the first and the most important thing to note is the surface temperature of the leaf. It will give you an idea of how much distance you should maintain.

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Some recent reports have shown that most leaves don’t get burnt if the temperature increases not more than 29 degrees Celsius. It shows that by maintaining a temperature of 20⁰, you can hang LED grow lights closer to plants. This will increase the soaking up efficient light as well as the utilization rate of grow lights.

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When deciding a distance between grow lights and your plants, you also need to consider PPFD. According to experts, it is the second most important factor after the leaf temperature. PPFD stands for photosynthetic photon change Density. It helps you gauge the amount of light that is required by a plant.

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As a matter of fact, when you change the length of LED grow lights, you are changing the amount of PPFD. According to experts, the normal PPFD required for plants is 400 umol/m²/s. The optimal PPFD is 1200 umol/m²/s that your plants soak up. If the value goes beyond 1200, It will not be soaked up by plants.

Through this discussion, you have to ensure that the PPFD value should be over 400 umol/m²/s. Any amount of light higher than 1200 umol/m²/s will be lost. It is very interesting to note that LED grow lights manufacturers give PPFD maps as well.

Moreover, it would be better if you keep a PAR meter. This will help you determine the PPFD values for your plants. You can adjust the length of your plants and grow lights according to determined PPFD values.

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Another important thing to note here is the type of LED grow lights. Now, basically, there are two types of LED grow lights present in the market. These two kinds are:

Bar LED Grow Lights

Board LED Grow Lights

Now, you must be thinking about why you need to consider the type of LED grow lights. Well, this is not very complicated to understand.

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Bar grow lights can be kept closer to your plants as compared to board LED grow lights. This may be due to the fact that bar lights are safer than board lights. You may also need to confirm the length based on the type of your grow lights.

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Development Stage Of Plants

The last important factor to decide the length between hanging grow lights and plants is the growth phase. The three most important Growth phases of your plants are listed below:

Seedling Phase

Vegetation Stage

Blooming Stage

All these stages correspond to different values of PPFD. For example,

● 400 umol/m²/s for the seedling phase.

● 400-800 umol/m²/s for vegetation phase

● 800-1200 umol/m²/s for the blooming or flowering phase.

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The length of your full spectrum led grow light can be changed according to its growth phase. Just remember that any amount of light more than 1200 umol/m²/s will be lost.

As a matter of fact, there is no exact length to keep between your plants and the lights. You have to keep adjusting it according to real-life circumstances. This all depends upon certain factors such as leaf temperature, PPFD, and different growth phases.

Most effective length

According to expert farmers, the most effective length is 10-20 inches for your plants. With the vast majority of new technologies developing these days, there is a new dimming feature in the best LED grow lights.

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Dimming Feature:

The dimming feature allows you to adjust the length of your plants according to different growth phases. Moreover, you can increase the illumination or dim it according to the needs of your plants. It is interesting to note that the dimming feature also saves a lot of energy and power consumption hence saving the electricity bills. The basic purpose of growth light is to have sufficient light for your plants.

In simple words, all that has been concluded is that you can adjust the length based on the above factors. You can also ask your fellow growers to be Helpful in this regard. It might also be affected based on the type of your plant. Some plants may need close distance while others don’t want that much closeness. So choose length carefully.


Adjusting the right Length for your grow space might be hard for you. This is why this blog has been written as a guide for you. If you are still confused about choosing the right length then you should consider reading the user manual. If it’s still not helpful for you then should consider talking to your manufacturer. Some cheap LED grow lights manufacturers also help you in this such as spider farmer, cob led grow lights, and mars hydro grow lights.





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