The Solar Greenhouse That’s Right for You
Here is a new gardening tool that produces
fresh food when the snow flies.
JACK RUTTLE
ALMOST ANY STRUCTURE that is built to look like a solar greenhouse will work. That is to say, the solar greenhouse concept is so right that you can ignore (or not know) the fine points of solar design and still build a house with much less need for supplemental heat than a traditional greenhouse. But once you understand a few basic solar-greenhouse design ideas, you can easily put together a greenhouse that truly lives up to the label solar, and provides remarkable efficiency.
Dave MacKinnon, Ph.D., ORGANIC GARDENING greenhouse designer, has put it all together after three years of experimenting and has created a design formula that gardeners in any climate can follow. His newest solar greenhouse, which he has built and tested in Flagstaff, Arizona, epitomizes a good solar shape. It has produced food through two winters without requiring any outside heat source. Almost all the floor space is usable for growing beds because the energy storage is on the walls. And it uses a minimum of materials because the design, insulation and heat storage are in balance and arranged to complement each other.
The best measure of a solar green house is the plant-growing environment it creates. When the building is skillfully made, you will get midspring soil and air temperatures in the depths of winter on sun power alone.
Our experiences suggest that solar greenhouses can maintain that kind of environment in most parts of the country. ORGANIC GARDENING researchers have built two different greenhouses that have worked well despite unusual winter weather. The Flagstaff greenhouse performed well with much less sun than is considered normal, and the one at our Maxa-tawny, Pennsylvania, research center worked through the coldest winters in recorded meteorological history.
In December and January we harvested enough salad greens every day for three or four people. Cold-hardy plants, all very rich in vitamins A and C, produce best. Escarole, lettuce, parsley, corn salad, chervil, chives and other salad herbs are dependable. So are kale, chard and chicory, which grow so thin and tender in the weak winter sun that they are best in salads too. In spring and fall the harvests are bigger. Succession plantings make heat-loving plants like tomatoes and cucumbers possible far beyond their normal seasons.
