How Many Watts Per Square Foot for Led Grow Lights

Each weed indoor grower knows that using best LED grow lights is essential for the plants’ proper and natural growth. For some growers, using LED grow lights comes with some questions, such as how many LED watts grow lights a square foot of indoor space needs.

However, the question does not have an exact answer to it. The watts of LED grow lights needed for each square foot depends on the following key factors.

How Many Watts Per Square Foot for Led Grow Lights

Factors To Take Into Consideration When Choosing Watts Per Square Foot For LED Grow Lights

The following factors lay the largest role in determining the watts per square foot for the LED Grow lights.

Nature Of Your Crops

The type of crops you choose to grow in your indoor space will determine the light needs. Led grow lights come with varying watt power, and come crops require LED grow lights specially designed for them.

You may find that some grow lights will do only well with crops such as succulents, herbs, vegetables, and other small plants only. You will also get lights that are good for the same plants but do not come with any limits. Other factors to consider on the nature of the crops are as follows.

Plant type

Some plants such as weed, tomatoes, and pepper, require high light intensity while many others, such as herbs, thrive well with average to low light intensity. In this case, if you are growing plants that need more light than others do, you will need lights with more wattage.

Stage of growth

Each plant’s growth process goes through several phases, starting from seedling to germination, vegetative, and flowering. Each of the phases requires different light intensities. For example, during germination, plants require little or no light at all.

However, as the plant continues to grow, the need for light intensifies, as seen during the vegetative and flowering phases. The flowering phase needs light, but the same stage also needs to go through more darkness hours. The light requirement during this stage helps with the production of larger buds.

The numbers of plants you have in the indoor grow space

How many plants are you growing in your indoor space? If you have a high number of crops, you will need to increase the light intensity to allow each of the plants to get enough light.

Grow Tent Size

Grow tent size is another factor to take seriously if you are to determine the LED grow watts. If you have a large grow tent, you will require a higher light intensity than you would with a smaller one.

LED Grow Lights Type

Besides having different watt levels, LED grow lights also come in varying other factors. LED grow lights differ in their heights, color spectrums, and heat outputs. You can use the same watts on plants and yield different harvests.

  • Color spectrums

If you want the best growth for your crops, you have a mixture of colors from your LED grow lights. Using one color spectrum such may provide you with plants that come with one deformity or another.

White color LED grow lights mimic the sun’s natural light, which is great for the crops, but it comes with yellow and green lights that do not provide any benefits without other light spectrums.

Adding red, blue, UV, and IR lights guarantee a healthier plant. This makes multi-colored or full-spectrum LED grow lights a favorite with a good number of weed growers.

  • LED grow light height

Height or distance between the plant and the LED grow light also determines the amount of wattage you need for the grow space each time you change the grow light’s height, the crops receive different amounts of light intensity.

  • Heat Output

Heat output is another important factor to consider when determining How Many Watts Per Square Foot for Led Grow Lights you need in your grow tent.

Even though LED grow lights produce the same amounts of heat during operation, you get the best results from low heat output grow lights. You can only get low heat output from grow lights that come with heat-reducing features to prevent overheating.

So, How Many Watts Per Square Foot for Led Grow Lights?

Square FtFootWatts
40(6×7)1280
36(6×6)1150
30(5×6)960
25(5×5)800
20(4×5)640
16(4×4)500
12(3×4)400
9(3×3)300
6(2×3)200
4(2×2)120
2(2×1)60

After considering all the above factors, we can answer the above question. To determine the wattage, your indoor space needs per square meter, measure the grow tent width and multiply it by the length, then buy lights with the intensity to match the space.

How Far Should Led Grow Lights Be From Plants

Cannabis plants require lots of light to grow big buds, but you need to increase the light levels depending on growth stages. When creating the height difference, you also have to bear in mind that lights come with different brightness and heat output levels depending on the brand.

Unlike other grow lights such as the HPS OR MH, it is not easy to determine the distance needed between LED grow lights and the plants. For the best distance, you should consult the manufacturer of the LED grow light. However, the chart below is the closest to the height LED grow lights need to be from the plants.

WattageDistance Between LED Grow Light And Top Of The Plant (Inches)
200-399

12-20

400-599

20-27

600-799

30-38

800-999

32-42

1000 Plus

36-46

Wrapping it up

LED grow lights are the best lights to use for marijuana indoor growing. Unlike many other lighting systems, the lights provide the crops with better wattage per square foot without harming the crops from too much brightness or harmful chemicals.

Lights provide the crops with better wattage per square foot without harming the crops from too much brightness or harmful chemicals. They also come with modern full-spectrum lighting panels and last longer.

With the above details, you can choose the correct wattage for your indoor space.

Bowden draws from over a decade of home growing experience as well as consulting for small-scale and hobbyist-level growers. He has written hundreds of articles, thought pieces, and tutorials about growing cannabis at home

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