How to Use Fluorescent Lights for Growing

Thanks to the light-giving power of fluorescent growlight, plants can be grown indoors with no help from the sun. Many types of fluorescent lights are available on the market today, but only industrial, full spectrum, daylight, plant growth, actinic, tri-phosphor and special-purpose fluorescent lights provide the light spectrum needed for plant growth. Suitable fluorescent bulbs or tubes are found at most home-and-garden centers. You also will find the fixtures necessary to suspend the lights above the plants.

Hang the light fixture over the plant according to the manufacturer's instructions so that the bulbs will be between 6 and 12 inches above the topmost tip of the plant. The fluorescent light fixture must be adjustable. Hanging the fixture by chain and s-hook suspended from the ceiling is a popular setup. Fluorescent light intensity drops sharply below the plant's needs when it is farther than 12 inches from the plant. As the plant grows, lift the light so that the distance between the plant and the tubes remains constant throughout the plant's life.

Center the plant under the light fixture. The center of a fluorescent bulb produces more light than the ends of the bulb. If more than one plant is placed under the bulb, space them far enough apart so that the leaves of one plant do not block the light of another.

Install the fluorescent lamp into the fixture according to the manufacturer's instructions.

Keep the lights on for 16 to 18 hours daily if the plants will receive no outdoor light. They will only need 12 to 14 hours if light from a nearby window is available to the plants. Turn the lights on at daybreak. A 24-hour timer installed in the fixture (available at most electrical supply houses) will make turning them on and off in a timely fashion much easier.

Replace your fluorescent tubes once every six months, or at least annually, even if they still appear to be in working order. After six months, fluorescent tubes go through a process called cathode decay, in which they produce exponentially smaller amounts of light as they age, although they may look just as bright.