Grow Light Wattage per Square Foot

While you may use watts per square foot to give you a rudimentary idea of how much lighting you need, don’t rely on it as a measure of overall effectiveness. Remember, a lamp that uses a lot of power does not necessarily put out a lot of usable light, potentially leaving you with a hefty electric bill and wimpy plants.

If you are growing tomatoes in an area of your home or in a grow tent, many sources will recommend about 40 watts per square foot to properly light tomatoes.

Gardening Under Lights Book