THE FIRST heavy frost in the fall puts an end to most vegetables from the garden. There is a way to harvest some through the winter with a solar greenhouse.
Using a solar greenhouse is less expensive than using the regular kind, which must be heated.
The heat source of the solar greenhouse is primarily the sun. "A glass greeenhouse is a natural heat trap," according to John H. Pierce, author of a fine reference book, "GreenhouseSee VEGETABLES, Page 2, Col. 1 VEGETABLES, From Page 1 Grow How" (published in 1977 by Plants Alive Books, Seattle; 241 pages; well illustrated; $19.95).
"The short wave radiation energy from the sun, in the form of light, easily goes through the glass of the greenhouse and once inside, the energy is converted to heat in the form of long waves that will not pass back through the glass as readily as light," says Pierce.
"There are some simple methods of trapping solar energy to heat your own greenhouse. If you use a 55-gallon drum full of water or stones to support a bench in your greenhouse, for example, and let the sun shine all day on the black side, it will act as a collector.
"When the sun goes down at night, the drum releases heat to the air of the greenhouse. This simple structure is a solar heater that collects, stores and releases the energy of the sun," Pierce writes.
A new book, "Growing Food in Solar Greenhouses -- A Month-by-Month Guide to Raising Vegetables, Fruits, and Herbs Under Glass," by Delores Wolfe (Doubleday, 191 pages, well illustrated, $10.95 paperback), provides instructions on what to plant and when, how to start seeds and transplants, how much and when to water and fertilize, and how to control insects and diseases.
"Most of the cold-loving leafy salad greens do very well in a protected environment and can even stand a little frost when the night temperatures are low, even below freezing, during long-lasting cold spells," according to Wolfe. "It is possible to reap up to half-a-pound of greenery each day, if you observe just a few do's and don'ts.
"Chinese members of the cabbage family (brassicas) are very well adapted to cool climates and provide a variety of tastes for salad, soups and stir-fry dishes. Bok choy is very popular, as are gai choy, dai choi, seppaku taina and kyo mizina.
"Leaf lettuces, buttercrunch, grand rapids, kagran, oak leaf and salad bowl are hardy and good producers. Grow several types for a variety of color and flavor in the salad bowl.
"Endive, chicory, kale, and swiss chard add variety to meals. Chervil and parsley, used as garnishes, and most other herbs, also do well during cold weather.
"Snow peas and sugar snap peas (edible pea pods) can be grown in fairly small spaces if trellised. Succession plantings timed every two weeks will keep peas available until spring plantings can be made outdoors.
"Vegetable plants bearing fruit, such as tomatoes, may do poorly in the cool greenhouse because they require warm days and nights to set fruit."
Tomatoes for Christmas must be started soon after the summer solstice on June 21 to mature before mid-October. They do better if allowed to reach maturity before the greenhouse environment becomes cool and the days grow short. Plant energy must be directed to maturing the crop rather than the plant, when poor light and cool temperatures slow growth in most plants, from the first of November to about the first of March.
Cherry tomatoes are an excellent choice for the winter greenhouse. They are more tolerant of adverse conditions and are vigorous producers of sweet fruit.
As fall progresses, bring in kale and other greens that do best after being nipped by frost. Oriental vegetables, lettuce, beet tops and chard love low light, so ready them for the November-to-March garden.