Fluorescent grow lights are an economical choice for your plants, costing as little as 10 cents a day to run. They are recommended for starting seeds and cuttings, in addition to growing herbs and low-light plants, such as African violets. Carol Yaw, owner of Charley's Greenhouse and Garden Supply Company in Mt. Vernon, Washington, says: "Fluorescent lighting is the first choice of most hobby gardeners, offering a good compromise between cost and quality of light for growing plants."
High Output Fluorescent Tubes
Choose lighting and fixtures designed for plant growth. Plant fixtures direct the light downward and are usually painted on the inside to reflect light. Fluorescent grow lights are designed with a larger spectrum of light. There are two types of fluorescent lighting: high-output fluorescent tube lamp; and high-intensity compact fluorescent bulb. The high-output fluorescent lamp is available in sizes T-12, T-8 and T-5, and comes in lengths of 2 or 4 feet.
'T' Series Tubes
The T-12 fluorescent light is a wide-spectrum light for growing foliage and flowering plants, and works best with plants that have an additional light source. The T-8 fluorescent light is a full-spectrum, high-output light that uses fewer watts. There is a T-8 available that is brighter, and is considered a sunshine lamp. The T-5 lamp comes in two types. One is full-spectrum and high-output light; the other has more orange and red spectrum, to promote budding and flowering.
The T series of lights produce more light per watt. The tube-shaped lamps are more energy efficient, produce less heat and are powered by instant-start, flicker-free electronic ballasts. "It is important to remember that fluorescents emit less and less light as they age," Caw says. She suggests replacing the bulb each year for best results. The T series tubes are not interchangeable between fixtures because the tube ends are different. However, there are adapter kits available.
The high-intensity output fluorescent bulb uses a standard incandescent light socket. The bulb is full spectrum and provides more light without damaging the foliage. This bulb is a good choice for small hobby gardens. The bulb is available is several wattage sizes. It uses 80 percent less energy and lasts up to 10 times longer than an incandescent bulb. Since the bulb can be placed closer to the plant, the light intensity is increased.
There are a few terms that will help the gardener in choosing a grow light. Kelvin is a unit of measure for temperature. Lumen is a unit of measure of light, or a way to measure how much light gets to what you want to grow. Watt is a unit of electrical power. Color temperature is a measurement in degrees Kelvin that indicates the hue of a specific type of light source. Natural daylight is 5500 to 6500 Kelvin, and will be stated as "K=5500 to K=6500." A fluorescent lamp will have a range of K=3200 to K=7500, depending on the style or type.