Greenborough, Vt. — It's been a long, hot summer so far. Even here on the old post road to Canada, Lewis Hill's mountainside nursery has had its share of sizzling temperatures. But the tall, lean nurseryman isn't fooled. The heat just visits here, he says; it seldom hangs around.
That's why he's planning now for the salad garden that will put fresh greens on the table even when pond ice is too thick to crack with a sledgehammer.
On six occasions during the past decade, the most bitter winter temperatures in all of the continental United States were recorded right here in Lewis and Nancy Hill's front yard.
Moreover, three months without a heavy frost constitutes a respectable growing season in this neck of the woods. But such bitter temperatures prove no deterrent to growing garden-fresh greens year-round because of a new design in solar growing frames that was tried out here last winter.
Agricultural experiment stations from around the nation send trees and shrubs to Hillcrest Nurseries for testing. If they mature at Hillcrest, so the reasoning goes, they'll mature anywhere this side of Fairbanks.
The Rodale people (publishers of Organic Gardening magazine) apparently thought the same thing about their new grow frame: If it works at Lewis Hill's nursery, it'll work everywhere. It did, so a satisfied Rodale Press went ahead and produced detailed but simple-to-follow plans for the winterproof grow frame.
Included with the plans is a book giving step-by-step building information, speciallized gardening data, and a list of the crops best suited to the winter grow frame.
Now anyone should be able to duplicate the Hill's experience and eat fresh out of the garden even in snowshoe weather.
It took several years and many phototypes before the Rodale engineers arrived at the present high-backed design that produces a comfortable winter growing climate for cool-weather crops without any subsidiary heat. In other words, it has advanced far beyond the conventional cold frame.
An almost airtight design that cuts hot- air leaks to a minimum; heavy insulation of both the frame itself and the soil, reducing conducted heat loss to a minimum; and thermal mass that effectively stores the sun's heat for night release are the keys to its success.
Research has shown that the need for light during the short days of winter is even more important to effective plant growth than warm soil.
On a visit to the Rodale experimental farm near Maxatawny, Pa., this past March, I saw the luxuriant growth in the test frames and later ate fresh salad, soup, and stir-fried dishes using vegetables direct from the grow frames.
Most of the vegetables grown are of the cabbage family, but in the protected indoor conditions of the grow frame they are much sweeter and more succulent than when grown outdoors. Three non-Oriental vegetables that do well in the grow frame are Swiss chard, endive, and spinach.
Soil in a grow frame should be rich in plant nutrients and contain plenty of organic matter to store moisture, yet be light enough to prevent water logging.
Organic matter also produces carbon dioxide which, through photosynthesis, is processed into plant tissue. Because available plant nutrients are frequently locked up in soils below 50 degrees F., it is necessary to apply a liquid fertilizer once a week. Manure or compost "teas" are good, but so are fish emulsion and liquid seaweed. Make sure they're well diluted.
It has been estimated that at current prices, the cost of new materials for the grow frame will come to approximately $250. Average construction time has been put at 40 hours, including drying time.
A most important contruction feature is to apply wood preservative to each section before it is hammered into place.
"That's the only way to thoroughly protect your investment" against degradation in the moist environment of a grow frame, asserts Ray Wolfe, editor of the grow frame book.
Bookstores will be able to order the grow-frame book for you or else it is available for $14.95 from Rodale Plans, Rodale Press, 33 East Minor Street, Emmaus, Pa. 18049.