The Ultimate Guide to Help You Choose the Correct LED Wattage for Your Grow Space

Are you new to the world of LED growing? If so, the charts below will help you determine how many LED watts your plants require.

But before we get into the juice, you must understand that the number of LED watts that you need for your grow will vary depending on:

    • Plant type (high light or low light)
      • High light plants - i.e. cannabis and tomatoes
      • Low light plants - i.e. herbs and leafy greens (such as lettuce)
    • Total area of your grow
      • A larger grow area will require more LED watts

Related: The best LED grow lights for 2016

LED Wattage Chart Explanation

Each section ('High Light Plants' or 'Low Light Plants') is dvided into 3 charts depending on the square footage that each plant might cover (1.0 to 4.0 sq ft for high light plants and 0.5 to 1.0 sq ft for low light plants).

In each chart you will find the following columns:

      • '# of Plants' to be grown
      • Square footage that the respective number of plants cover
      • Recommended LED wattage for the number of plants grown in the respective space

The listed wattages are actual LED wattages, not advertised wattages. See our discussion on the difference between advertised and actual LED wattages (second heading on page).

Remember, you can scale these values up if you are growing more than the number of listed plants or if your grow space is larger than we suggest below. 

Important: PPFD and DLI should be taken into consideration when choosing a light recipe for your grow. Wattage should only be used as a simple method for approximating the correct size light(s) for your grow.

Related: Why LED watts do not really matter to a plant and why PPFD and DLI do

 

High Light Plants (cannabis, tomatoes, etc)

Require ~25 watts/sq ft (actual LED wattage)

 

Assuming 1.0 sq ft/plant

 # of Plants   Square Feet   Recommended LED Wattage
1 1 25
2 2 50
4 4 100
6 6 150
8 8 200
10 10 250

 

Assuming 2.0 sq ft/plant

 # of Plants   Square Feet   Recommended LED Wattage
1 2 50
2 4 100
4 8 200
6 12 300
8 16 400
10 20 500

 

Assuming 4.0 sq ft/plant

 # of Plants   Square Feet   Recommended LED Wattage
1 4 100
2 8 200
4 16 400
6 24 600
8 32 800
10 40 1000

 

Quick Chart: Recommended LED wattage for high light plants (25 actual watts/sq ft)

1' x 1': 25 watts

2' x 2': 100 watts

3' x 3': 225 watts

4' x 4': 400 watts

5' x 5': 625 watts

6' x 6': 900 watts

 

Shop LED Grow Lights for Cannabis ›

 

Low Light Plants (leafy greens such as lettuce and basil)

Require ~16 watts/sq ft (actual LED wattage)

 

Assuming 0.5 sq ft/plant

 # of Plants 
 Square Feet 
 Recommended LED Wattage 
1 0.25 4
5
2.5
10
5
15
7.5
20
10
25
12.5

 

Assuming 0.75 sq ft/plant

 # of Plants   Square Feet   Recommended LED Wattage 
1 0.5 9
5 3.75 60
10 7.5 120
15 11.25 180
20 15 240
25 18.75 300

 

Assuming 1.0 sq ft/plant

 # of Plants   Square Feet   Recommended LED Wattage 
1 1 16
5 5 80
10 10 160
15 15 240
20 20 320
25 25 400


Quick Chart: Recommended LED wattage for low light plants (16 actual watts/sq ft)

1' x 1': 16 watts

2' x 2': 64 watts

3' x 3': 144 watts

4' x 4': 256 watts

5' x 5': 400 watts

6' x 6': 576 watts

 

Shop LED Grow Lights for Leafy Greens ›

 

Are you a beginner grower? You might also be interested in the following books:

   

  

 

Related: See what else you should consider before purchasing a LED grow light

Disclaimer: All LED grow light 'Descriptions' and 'Specs' stated by LED Grow Lights Depot are the claims of the original manufacturer and/or supplier and not LED Grow Lights Depot. We do our best to ensure the information is accurate and correct.

Notes: Please be aware that the cultivation of certain plants may or may not be legal within your own specific region or country. LED Grow Lights Depot does not encourage or condone any illegal activity and advises each individual / user to inform themselves of the relevant laws within their own region/country.

The book links are affiliate links. Therefore, we make a small commission if you decide to purchase these products from Amazon.