Indoor gardening with fluorescent light tubes allows gardeners to get an early start in the spring, extend the growing season come winter and grow healthy houseplants year round. Most plants will grow under lights if a few basic conditions are met.
The Right Bulbs
"Grow light" or "sun-light" tubes produce a complete spectrum of light, while "cool white" and "warm white" bulbs produce more blue and red light, respectively. Full-spectrum fluorescent tubes may cost 10 times more than cool white and warm white tubes. Many growers use a combination of cool white and warm white tubes for a complete but less costly light spectrum.
Number of Bulbs
Light intensity is adjusted by adding or removing light bulbs. A single, 4-foot, 40-watt tube provides 10 lamp watts per square foot. Experts recommend 10 to 15 watts per square foot (one or two tubes) for germinating seeds; 15 to 20 watts (two tubes) for houseplants and seedlings; and 25 to 30 watts (two or three tubes)—or even more—for vegetables and flowering plants.
Distance of Bulbs
The closer the bulbs to the plant, the more intense the light. Bulbs placed six inches from plants provide approximately 600 foot-candles to the leaves (perfect for most houseplants). Bulbs placed two to three inches from plants provide 1,000 foot-candles (perfect for seedlings, flowers and vegetables). Attach light fixtures to chains to make them adjustable.
Some plants grow better under fluorescent light than others. Low-light houseplants flourish under artificial lighting; light-loving plants, such as some vegetables, might struggle. For plants that require intense lighting, such as flowering and fruiting plants, more fluorescent tubes are needed.
Plants need periods of light and darkness to metabolize and produce food. Placing fluorescent lights on a timer will ensure these requirements are met. Provide most plants with 12 to 16 hours of light per day—less if light is received from a window. Some plants flower in response to photo-periods—or the length of the day and night. These plants need special lighting schedules.
- National Gardening Association: The Facts of Light
- Fine Gardening: Indoor Plant Lights
- University of Missouri: Lighting Indoor Houseplants
- Plant Biology: Photoperiod Response
- Oregon State University: Long and Short Day Plants
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About this Author
Charles Thomas has been a freelance writer since 2005. He is an active contributor to the "Van Nuys News Press," including its "Government Center Gazette." Thomas is pursuing a Master of Arts in anthropology at California State University-Northridge.