How many plants can 1 LED grow light grow?

How much light is enough to promote excellent growth in my plants?

That’s a question a lot of growers ask themselves at some point when trying to decide on the best grow light for their plants. Whether you’re new to growing or you’ve been growing for a long time, figuring out how much light you need can be tricky.

If you’re feeling overwhelmed, don’t worry. We’ve created this guide to help you determine exactly how much light your plants will need in a grow tent or grow room environment.

Light Coverage

Knowing how much light your plants need isn’t as simple as choosing any light and then hoping for the best. You’ll have to take into account two important factors:

Plant Coverage — This is pretty self explanatory and means the amount of light each individual plant will receive.
Canopy Coverage — This type of coverage refers to the light that will be spread over the entire group of plants in your grow tent, otherwise known as the canopy.
Whether you’re going with plant coverage or canopy coverage, it’s essential to know how much PAR or lumens you’re going to need for optimal growth. Remember:

Lumens measure the intensity of an HID light, which includes HPS grow lights, MH grow lights, and CMH grow lights.
PAR, or photosynthetically active radiation, is used to measure the intensity of LED grow lights.
You might be asking yourself, “Why do I need to factor lumens/PAR? Can’t I just use a certain number of watts per square foot in my grow room?” While you could just base the amount of necessary light for your plants on the size of your grow room or grow tent, doing so won’t give you enough light intensity for all of your plants.

Plants require a certain amount of lumens or PAR to achieve optimal growth.
As such, it’s best to figure out the exact amount of lumens/PAR the specific plants you’re growing will need.
Notice that we’re ditching the whole “x-watts/per sq.ft.” method. Now, the coverage area of any given light will have varying PAR/lumens the further out from the center you go. That’s why if you have a large growing area and need to use multiple lights, PAR and lumens is going to be especially handy.
This will allow you to figure out how much light they need more accurately than just trying to get a certain amount of wattage per square foot.

Watts per square foot
The average LED grow light draws about 32 watts to cover 1 sq ft for flowering. Compare this to a typical HID fixture which rings in at 40 watts per square foot (assuming a 5’ x 5’ area, or 25 sq ft coverage area). Using an HID in a 4’ x 4’ will bring the power coverage up to 62.5 watts per sq ft. (The energy saving that growers can expect from using LED grow lights instead of HID is around 38%. This energy savings only takes into account to savings growers gain when using LEDs fixtures. It does not account for other environmental factors where growers can save energy. For example, less ventilation and air conditioning may be used, or foregone completely, depending on the size of the setup and ambient temperatures. Total power savings may rise above 50% in certain scenarios.)

Different LED grow lights will have different efficiencies. More efficient LED grow lights will use fewer watts to emit the same amount of light that a less efficient LED grow light will exude. Therefore, as mentioned above, wattage is not the most accurate tool to know how powerful of a grow light you need for a particular coverage area.

How Many Plants Can I Grow?

In general, each cannabis plant you grow requires at least 1sq ft of space.

After germination, I like to place one plant in a large 5-gallon fabric container, which has a diameter of roughly 1 sq foot.

My plant will stay in this pot until it flowers.

This allows the plant to grow big and strong without other plants or tent walls obstructing its progress. I also don’t like transferring plants too often, as it puts a lot of stress on the plant.

So this as a guideline, I would be able to grow between 1–6 plants in my example above.

Make Sure Your Canopy Is Covered

Now, it’s also important to understand that LED grow lights for plants will usually only be able to cover around 1- 6 plants.

If you want to grow any more plans than this, you would need to purchase multiple lights to hang side by side ( called daisy-chaining ) to cover the canopy and ensure each plant is getting equal light.

The table below shows how the number of watts you require increases with the size of your grow space. I’ve also included how many plants each size of grow light will be adequate for.

Note: 1 sq ft grow space = 50 watts LED grow light

Best LED Grow Light for First Indoor Growers

ECO Farm 240W LM301B/LM301H Classic Quantum Board

This lightweight LED grow light is 40% more energy efficient compared to its non-LED competition. Its ability to mimic natural sunlight makes it perfect for all stages of a plant’s life, including seedling, vegetation, and bloom.