How to Use Growing Lights


Growing lights supplement or replace the need for natural sunlight when starting seeds or caring for indoor plants. There are a variety of light setups available at garden centers. Most consist of one or more fluorescent tube lights in a height-adjustable fixture that allows for use with the smallest seedlings or large houseplants. While special grow light tubes are available, using a cool white light and warm white light also supplies the proper light spectrum without the need for the expensive grow light fluorescents.

Step 1

Check the light requirements on the seed envelope or plant tag. Most vegetables require six to eight hours while houseplants are labeled low-, high- or medium-light. Supply high-light plants with six to eight hours and medium-light with four to six hours. Low-light plants usually require no additional light from growing lights.

Step 2

Adjust the fixture until the lights are 4 inches above seedlings and 6 to 8 inches above the tops of established plants. Adjust the fixture as the plants grow to maintain the same distance between the lights and the plants at all times.

Step 3

Plug the light into a timer so that it turns off and on automatically. Set the timer to be on for twice as long as the natural light requirements for a plant. For example, leave the light on for 12 to 16 hours for high-light plants.

Step 4

Check that the light is bathing the tops and sides of the plants. Place a plastic reflector, available at home improvement stores, over the light to reflect it onto the sides of the plants if necessary. Place plants in a single row under narrow light fixtures or leave 4 inches between plants under wide fixtures to allow enough light to bathe the sides.

Step 5

Check moisture levels in the growing pots daily. Water when the soil surface begins to feel dry. Plants under lights do not dry as fast as containers outside, so take care not to over-water.

Tips and Warnings

  • Do not let the foliage touch the light bulbs as it may burn the leaves.

Things You'll Need

  • Timer plug
  • Light reflector


  • North Dakota State University: How to Succeed at Seed Starting
  • Colorado State University Extension: Houseplants Artificial Light
Keywords: growing lights, plants and fluorescent lights, growing indoors

About this Author

Jenny Harrington is a freelance writer of more than five years' experience. Her work has appeared in "Dollar Stretcher" and various blogs. Previously, she owned her own business for four years, selling handmade items online, wholesale and via the crafts fair circuit. Her specialties are small business, crafting, decorating and gardening.