How Many Lights Do You Need For Your Grow Space?

Are you new to the world of LED growing? Once you know how much light your plants need and what type of grow lights you are going to use, it's just a matter of choosing a grow light setup that works for you.

What are you growing?

Before you decide on an LED grow light, you must consider your crop. All full-cycle, quality LED lights sold on the market will grow a plant from seedling to flower. But some lights are designed for specific types of grows. LED grow lights used to grow indoor medical plants from seed to flower.

There are important things you need to know before beginning:

  1. Light Requirement

For the light requirement, you really only need to know if it has a high light requirement or a low one.

  • Plants that flower or bear fruit, such as tomatoes, fruit trees, flowers and the like, typically have higher light requirements, usually around 40 watts per square foot. 
  • Plants that do not flower or fruit, such as medicinal plants and lettuce, can do well with lower lighting. The prefer 25-30 watts per square foot.
  • If you are growing more than one plant type, you may need to set up your lights accordingly.The high-performance plants can be placed together in one area with more watts per square feet, with the other plants having fewer lights.
  1. Calculate your grow light requirements

A common mistake new growers make is measuring the dimensions of the grow room itself.

What you really should be measuring is the footprint of your plant canopy.

For example, if you are growing in a 5’ x 5’ space but your plant canopy only takes up 4’ x 4’, you don’t need a grow light capable of lighting the 5’ x 5’ space - it would be overkill.


  1. Determine your plant’s lighting needs (watts/square foot)

Low light plants, such as medicinal plants and lettuces require about 11-18 watts per square foot of grow space. However, this will vary with crop and preferred light levels. Below is a quick reference chart designed to help you determine the desired wattage based on your grow space. If you have a larger grow space, you can scale up from these numbers. Remember: 1 sq ft of grow space requires about 32 watts of actual wattage. 


Grow Space


2 sq ft (2x1)


4 sq ft (2x2)


6 sq ft (2x3)


9 sq ft (3x3)


12 sq ft (3x4)


16 sq ft (4x4)


20 sq ft (4x5)


25 sq ft (5x5)


30 sq ft (5x6)


36 sq ft (6x6)


40 sq ft (6x7)



So, how many plants can you grow then?

Let us divide 32 watts per square footage. In this example, let us say you have 5 plants in a 6 square feet space.

5 X 6 = total footage is at 30 square feet

30 square feet X 32 watts = 960 watts LED grow lights

Here are some more samples for different plant quantities and area coverage:


Actual LED Watts

Units of LED Grow Lights


128 watts

1. 120-140 watts


192 watts

1. 180-240 watts


256 watts

1. 240-280 watts OR (2) 120-140 watts


288 watts

1. 270-310 watts OR (2) 140 watts


512 watts

1. 420-480 watts OR (2) 240 watts


768 watts

1. 720-1,000 watts OR (6) 120-140 watts


800 watts

1. 750-1,000 watts OR (4) 180-240 watts


The height difference between LED light and the plant canopy.

The distance of the LED from the plant canopy has a direct impact on its light intensity. You have to always maintain the right and safe height to achieve the potential maximum yield.

Placing the bulbs too close to the cultivars runs the risk of burning, bleaching, and possible nutrient deficiencies. Meanwhile, hanging it too high up also reduces its efficiency to deliver the right amount of light to the plants.

The details below show the recommended LED grow light heights over the canopy.

LED Wattage


240-400 watts

16 to 30 inches

450-550 watts

20 to 30 inches

600-850 watts

24 to 26 inches

900 watts and above

26 to 42 inches


Best LED Lights Suitable for Your Plant Grow

ECO Farm ECOG 100W/200W/300W/400W/500W/600W Quantum Board With Samsung 281B Chips Waterproof LED Grow Light


  1. High Efficiency & Cost Saving: ECO Farm ECOG quantum board adopts the latest high-quality LEDs technology-Samsung LM281B diodes, high energy efficiency with 2.5 umol/J, delivers powerful light output and uniform canopy penetration to resulting maximum higher yields.
  2. Customized Dimming Design: Anadded dimmer knob is featured to manipulate the light intensity at liberty, reducing light lost to aisles and walls, provides desired needs for plants in all stages from seeding to bloom.
  3. Excellent full spectrum led grow light: white, blue, red, IR and UV (3000K, 5000K, 660NM, 730NM, 380NM), provides desired need for plant growth in all stages from seeds to harvest. 
  4. No Noise & Less heat-output: 4.0MM thick aluminum plate radiator, fast heat conduction, low temperature. Select a high-quality UL-certified power supply allows you to use the full spectrum plant lights in a moist grow tent/greenhouse, longer lifespan to speed up plant's grow processes and boost yields.
  5. Splicable, small size, high power, support for input series connection
  6. Certification: CE RoHS FCC
  7. Warranty: 3 years




ECO Farm 100W/150W/200W/290W Full Spectrum COB LED Grow Light



  1. Plants Veg and Flower all stages with everything they desire in the natural sunlight. ECO Farm COB LED Grow Light using full spectrum light for plants, largely accelerate the plant growth, provide things plants desired in the natural sunlight, encouraging healthier and more balanced plant growth by stimulating photosynthesis.
  2. Energy-saving, big lighting area and high LUX, small unit with high brightness and long work service up to 50,000 hours.
    This is newest light on the market, high light efficiency, very easily manageable temperature.
  3.  Ideal for all phases of plant growth, can be used in house garden, pot culture, garden, sowing, breeding, farm, flower exhibition, bonsai, garden, green house, sowing, breeding, farm, greenhouse cultivation, water soluble breeding, greenhouse cultivation, pipeline cultivation and so on.


As we end, it’s important to remind you that there is no universal guideline for the watts needed per square foot for LED grow lights. The requirement of the light wattage differs on various factor. Our official website is www. If you really need to find one suits your requirements, pls feel free to cotact us, no charge:)


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