Lighting away winter blues - using artificial light indoors to maintain containerized plants and flowers from the garden during winter months

Flower & Garden Magazine, Dec-Jan, 1993 by H.E. Gibson

Winter Solstice which occurs on December 21, marks the beginning of winter. It is considered the "shortest" day of the year because the Earth's Northern Hemisphere is titled at its widest angle from the sun. The period of daylight increases a little more each day thereafter until the summer solstice in June.

TThe additional minutes barely seem to make a dent in the long hours of darkness for gardeners yearning for spring. The solution is to re-create long hours of daylight indoors. With a little creativity, some tools, gardening supplies and an electrical outlet, you can make your own indoor greenhouse.

What you grow will be limited only by your imagination and the space you allocate. However, I advise starting small. There will be no spring showers to rescue your plants if you forget to water them or fertile soil to remedy missed fertilizer applications. Try saving some cuttings from your favorite garden plants and selecting some exotic flowers available only from seed. Once you've gained experience in gardening under lights, you'll find it ideal for growing many types of plants, from prize-winning African violets to spring bedding transplants.

WHAT IS LIGHT?

Plants require adequate light to perform photosynthesis, the process by which they make food from carbon dioxide and water. Sunlight, although it appears "white," actually blends a broad spectrum of light waves from ultra-violet to violet to blue to green to yellow to orange to red. The human eye can detect light only in certain areas of the spectrum.

Plants thrive in sunlight, which provides relatively even exposure to the different wavelengths of light. Standard household lighting tends to focus on the yellow light waves in the middle of the spectrum. However, there are some general differences in the types of light bulbs available. Incandescent light bulbs tend to have more light on the far red side of the spectrum. Cool white fluorescent lights tend to emit higher levels of violet and blue light than warm white fluorescent lights, but both types of fluorescent lights are high in the yellow and orange wavelengths.

There are several methods for balancing light to meet plant needs. The easiest solution is also the most expensive. There are several type of growing lights available. Sometimes these lights are called wide-spectrum or full-spectrum lights to indicate the range of waves they provide. In most cases, growing lights try to imitate the spectrum contained in sunlight. By purchasing these lights, you avoid the trouble of trying to figure out how to mix colors and wavelengths from different light sources. Growing lights range from $2 to $200, depending on the size of the bulb and whether it comes in a complete lighting kit package.

Another choice is to attempt a balanced light spectrum with one cool white and one warm white fluorescent bulb. Some people have had good luck using just standard light bulbs. Incandescent bulbs generate heat, however, so use them only where they won't dry out or burn foliage.

CHOOSING A LIGHT FIXTURE

You can create a simple, relatively inexpensive indoor greenhouse with a folding table, a hanging shop lamp, an automatic timer and a tray of gravel. The first step is finding a suitable location. An unused basement corner or a place in a heated garage works well. Try to locate the table as close as possible to an electric outlet so there won't be yards of extension cord to trip over.

Attach the hanging lamp securely to the ceiling and hang it by an appropriate chain. S-hooks can give you the flexibility to adjust the light height to match plant needs. Most lamps use two light tubes, so you can use either two growing lights, a mixture of a growing light and a warm white fluorescent, or one cool white and one warm white fluorescent tube.

Automatic timers are easy to locate. These switch the light on and off for set periods of time. Typically, you will want to mimic a spring day with about 14 hours of daylight. All plants need periods of darkness that resemble night. For the best results, try to maintain a regular schedule of day and night conditions.

A leakproof tray with drainage is a key element. Even the best designed growing flats will overflow or leak at least once during the growing period. A gravel tray will save cleanup time. You can use any available shallow plastic or rubber tray and fill it with inexpensive pea gravel.

Variations on these simple elements are endless. Creative do-it-yourselfers can invent numerous ways to build shelving and mount lights. Hardware stores and garden centers stock an array of light fixtures and wood to construct almost any size indoor growing area.

If you don't want to build your own, there are several pre-designed indoor lighting kits that provide the light fixture, bulbs, table and growing trays. Although some assembly is usually required, most come with easy-to-follow instructions. Some of these kits provide several levels of shelves with lights mounting above each shelf. These units fit conveniently against a wall, and the portable models on wheels are useful if you plan to move the unit.