One very gray spring it became obvious that the cabbage plants I was growing indoors would have four-foot stems if they didn't get light soon. We had a fluorescent fixture over the sink at that time and open shelves on either side, so I put books on the shelves and stretched curtain rods across them to position the seed flats directly under the light.
Most of the seedlings improved almost from the first day.
I resurrected the old light fixture and the combination of natural and artificial light in a cool place produced the best seedlings I had ever raised.
The point is, you can raise your spring plants without additional light, but the quality will be so improved that even the simplest light setup will pay for itself in one season. Here are the basic facts you need to know.
While some growers use incandescent lights in combination with fluorescent tubes, the latter are all you really need. Also, the incandescent lights used alone will do more harm than good because they produce more heat than the kind of light the plants need.
You can buy a special grow light if you wish, but a plain, cool, white fluorescent tube is, in some ways, even better and more efficient. If you have a 2-tube fixture, use one cool white and one grow light or one cool and one warm white fluorescent tube.
For peak efficiency get tubes that are at least 36 inches long. Shorter tubes cost more to run than they are worth.
Turn and rearrange the seed flats every other day so that those under the ends and the outside will grow evenly with those in the middle.
Be sure to give your plants at least six hours of total darkness out of 24. This is important because plants do a large part of their growing at night.
As a rule, the tops of the seedlings should be only one-half to three inches from the light tubes. If you have various plants growing at different rates and heights, you can lower or raise the individual flats. Otherwise, be prepared to raise and lower the fixture.
Reflect back upon the plants as much light as you can. Paint the surrounding shelves with a flat white latex paint or surround the flats with aluminum foil.
At least once a month turn off the lights and clean the tubes and reflectors with soapy water to get the most possible light on the plants. Be sure to allow the tubes to dry completely before replacing them and turning them back on.
Never spill or spray water on the lighted tubes. You could cause cracking or even an explosion of the glass. Never drop a tube, either, because it will break.
Avoid turning the lights on and off any more than necessary. Most people turn them on the first thing in the morning and then turn them off before they go to bed at night. There are automatic timers available to do this for you.
The tubes may still work, but they lose light power after a time and should be replaced. If you use them only in the late winter and spring, once a year is enough. Watch your plants for indications of too much light -- stubbiness or yellow or very dark-green color. Spindly plants should be put closer to the light -- or you need new tubes.
You can get a four-foot light fixture and reflector for about $12 to $15 and operate it for pennies a day. You will only need the light for a few months at most, but you may find you like it so well that you'll develop a whole new phase of year-round gardening.