New Market, Va. — Innovations in high-output fluorescent lamps are making the growing easier for people whose only garden options are in places where the sun won't shine.
Heated basements, windowless workshops, protected porches and other out-of-the-way enclosures can become nearly as functional as hobby greenhouses thanks to the new T-8 and even newer T-5 fluorescents, said Charley Yaw, president and owner of Charley's Greenhouse & Garden, a mail-order company based in Mount Vernon, Wash.
"These commercial lights have been adapted to 'grow lights' by providing the correct color spectrum that plants use for their growth cycles," Yaw said. "The 'cool' or 'daylight' (lamps) are also known as 'full spectrum' and are the best for indoor all-around growing. Their high proportion of blue spectrum is ideal for promoting green, leafy growth. The 'warm' lamps are strong in the red-orange spectrum and are used to promote flowering and fruiting."
This makes for more vigorous plant starts, no matter where the seeds, plugs or cuttings are set. Plants requiring high light levels also will grow more efficiently, making year-round gardening simpler.
That can mean walking into a room full of green, thriving plants even in the darkest days of winter. It also can mean being able to add fresh herbs to holiday recipes, inhale the soft scent of blooming tropicals or nibble on a few fresh cherry tomatoes.
High-intensity grow lights additionally give gardeners a running start on spring, germinating annuals long before the plant beds can warm outside.
Indoor growing introduces some new words to the game, including:
¢ Ballast: a resistor stabilizing the current in an electric circuit, primarily in fluorescent lamps. Gardeners should buy fixtures with good ballasts, which means passing up the ubiquitous and inexpensive "shop lights," Yaw said. "Those are designed only for short periods of use. The better the ballast, the longer the bulb lasts."
¢ Photoperiod: the amount of time per day that light is required for germinating seeds and cuttings. Flowers and vegetables, as a rule, need 10 to 12 hours of light each day. Flower- or fruit-producing plants may require 16 hours or more.
¢ Fluorescent: a tubular electric lamp coated with fluorescent material on its inner surface and containing a mercury vapor whose bombardment by electrons produces ultraviolet light. That, in turn, prompts the electrons to emit a visible glow. The coating determines which light spectrum is emitted.
¢ T-12, T-5, et al: "New lamps are a smaller diameter, which has enabled a higher output," Yaw said. "The number refers to the diameter in eighths of an inch. T-12, for example, equals 12-eighths, or 1 1/2 inches."
Recent improvements in plant light technology answer not only the needs of commercial growers but those of the huge residential market, people who bring their gardening inside when the weather cools.
"Forty-two percent of all households, or 46 million households, grew indoor houseplants last year and spent a total of $1.5 billion on plants, pots, soil and supplies," said Bruce Butterfield, research director for the National Gardening Association.
"Some 2.7 million households bought indoor plant lights last year, which is about the same number we have seen annually for the last several years. My best guess is that 10 to 15 million households grow plants indoors under lights."
High-output fluorescents generally are pricier than their outdated counterparts, but users appear to be getting their money's worth.
"The old and still available T-12 grow lights have an output of 1,500 to 1,700 lumens for a 48-inch lamp and a life of 10,000 hours," Yaw said. "The new T-8s have 3,400 lumens and a 40,000-hour life. The T-5 lamp is rated at 5,000 lumens and a 30,000-hour life.
"When you divide the cost of these high-output lamps by a seven- to nine-year life, at 12 hours per day, the cost per year is about $2.20 per lamp, plus electricity."
Another measurable efficiency: The new lights are cooler burning, which means they can be placed only a few inches from plants. Less light energy is lost.
While lighting is the all-important ingredient for indoor plant growth, gardeners can't ignore other needs: heat, humidity, air circulation, plant spacing and water.
Temperatures during lighting periods should run 70 to 75 degrees, and 60 to 65 degrees in the dark. Humidity should average 50 to 60 percent. Good ventilation is a must, especially when hardening off plants before setting them outside. Space helps seedlings resist disease, and develop thick roots and strong stems. Plants should be watered while the lights are on and the temperatures rising.