Fluorescent grow lights are useful for indoor gardening, either to start seedlings before eventually transferring them outdoors or to grow vegetables and other plants during the winter. If your home does not have a sunny room or windowsill you will need to use grow lights for any seeds that you start indoors. Seedlings will need plenty of light as soon as they poke through the soil, and using a timer to control when your grow lights turn on and off will help create an artificial "day" of sunlight for your plants.
Prepare your grow lights for use before you start your seedlings. Combine two fluorescent bulbs in a long fluorescent light fixture (available at any gardening or hardware store). For the best results, use one "cool" white tube and one "warm" white tube; each tube will provide different wavelengths of light for your growing plants. Fluorescent bulbs that are intended for growing plants will be marked as either cool or warm, and grow lights that come with two tubes already in the light fixture will have one of each type.
Hang the grow lights in the room where you intend to grow your plants. You will need a support frame that allows you to move the grow light up and down according to the current size of the plants. You can either buy a support frame intended for this purpose, or you can make one out of inexpensive PVC pipe. See the resources section for homemade support frame plans provided by Cornell University.
Put your seedlings under grow lights as soon as the seedlings poke through the soil. Place the grow light about three to four inches from the seedlings for the best absorption of light. Use an outlet timer to turn the lights on for 14 to 16 hours per day, and leave the lights off for the remaining eight to 10 hours.
Move the lights up as the seedlings grow to avoid scorching the plants. If the plants are touching (or almost touching) the light bulbs, it's time to raise the grow light a few inches higher.
Water your seedlings regularly, depending on the needs of your individual plants. Most plants thrive in soil that is constantly moist but not wet, but some plants need periods of dry soil in order to thrive. Read the directions that came with your seeds or seedlings for individual instructions.
Use an indoor plant fertilizer if you keep your plants inside for more than 10 to 12 weeks. Indoor plants do not have access to nutrients from the soil like garden plants do, so it's important to use a houseplant fertilizer for proper nutrition. Follow the manufacturer's instructions for applying the fertilizer.