How to Use Fluorescent Light Bulbs for Growing
Gardeners use lights indoors to supplement or replace natural light to start seedlings, to provide extra light to indoor plants and to grow vegetables, herbs or flowers indoors. There are several lighting options for the indoor gardener, but fluorescent lighting remains a good and thrifty option. Does this Spark an idea?
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Things You'll Need
- Adjustable-height light fixture
- Watertight tray
- Gravel or pebbles
- Clean planting containers with drainage holes
- Fluorescent grow lights or regular fluorescent lights in both orange/red and blue color spectra
- Automatic timer (optional)
- Sterile seed starting or potting soil with perlite or vermiculite to promote drainage
- Plants or seeds
- Fertilizer
Instructions
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Consult with your garden center to choose plants that require similar levels of light intensity, duration and color spectrum. Plants generally fall into low, medium and high light requirements. For low light plants, you need one or two bulbs. For plants that need medium light, use at least two bulbs. Plants with high light requirements often do not do well in indoor gardens, but if you would like to try growing these plants, you will need at least four bulbs.
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Choose full spectrum grow lights specially made for plants, or choose a balance of cool (blue spectrum) and warm (orange/red spectrum) regular fluorescent lights. The exact balance will depend on the type of plants being grown, with more orange/red needed for flowering or fruit-producing plants.
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Set up the waterproof trays on a table and fill with a layer of gravel or pebbles to elevate the containers. Fill the bottom of the trays with water to increase humidity, keeping the water level below the tops of the pebbles. Leave enough room in the tray to receive any overflow from watering the plants.
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Plant the seeds or plants in the containers using the potting soil, following the instructions on seed packets and plant tags. Leave the top quarter of the container empty to provide space for watering.
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Water the plants and fertilize as directed on seed packets or plant tags.
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Adjust the grow lights according to the package directions; adjust the regular fluorescent lights to that they are 4 inches above the tops of the plants. Set the timer to the proper amount of light for the plants you have chosen: between 6 to 18 hours. Provide at least 6 hours of darkness per night.
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Tips & Warnings
Adjustable-height light fixtures are available at your local retail garden center and online garden centers.
Standard fluorescent lights come in T-12 and T-8 varieties. T-8s are smaller and retain their light production more consistently over the life of the bulb. High output T-5 fluorescent lights are more expensive, but produce more light than standard fluorescent bulbs while remaining cool to the touch. Compact fluorescent bulbs are shorter and more focused. Grow lights are specially formulated to give light in the full range of the color spectrum and can be more expensive.
Using reflectors behind the lights and keeping the bulbs clean of dust will increase the efficiency and brightness their output.
Fluorescent bulbs are brighter in the middle, so put plants needing more light in the middle.
If plants begin to grow tall and spindly, they need more light. This may be a sign that the bulbs need replacing, especially if they are darkening at the ends.
