AMERICAN INTENSIVE SOLAR GARDENING

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Lea was working at the time as a consultant to the Kalwall Corporation, a manufacturer of building products. At Lea's urging, Kalwall developed a solar-friendly, fiberglass-reinforced plastic sheet glazing material that he dubbed Sunlite. This

Sunlite material was dramatically lighter than glass per square foot, and it turned out to have many applications for Lea's designs and for the solar industry as a whole.

Lea began thinking about how to build the smallest and simplest solar greenhouse possible. Standard freestanding greenhouses provide no net energy gain when the net energy of the food produced is compared to the cost of heating the unit in wintertime. Add-on solar greenhouses or sun spaces create an energy deficit when you compare the amount of food produced in them to the resources and energy used in their construction.

In 1976 Lea conceived of a gardening device that met all of his design requirements: it was inexpensive, easy to build, and used resources and energy wisely. We christened this device the Solar Pod. That fall we prepared a bed and planted it with lettuce, but we didn't place the Pod on the bed until February. When we shoveled off the snow and uncovered the bed, which we had protected with a scrap of fiberglass, to our surprise the lettuce still looked green and edible underneath all that snow.

After we set the Pod in place, we were amazed by how the soil under it heated up and how the lettuce grew...and grew, and grew. It was quite possibly the most photographed lettuce in history. Friends came to see the experiment, and they mentioned to us that the Pod reminded them of intensive gardens in France. The following winter we discovered several books on French intensive gardening, or what the French call the Marais system.

Marais practitioners placed bell-shaped glass jars, or cloches, over individual plants or groups of seedlings to provide heat and protection and to create a microclimate underneath the glass. They also used extended cloches, which looked like what we would call cold frames. The cloches were used to preheat soil for planting and to cover seedlings and small plants; the glass- topped frames were set over plants that would be grown to maturity. In cold weather, woven straw mats placed over the glass at night provided a limited amount of insulation.

Solar Appliances

During the 1970s we lectured extensively all over New England on passive solar use and on our gardening methods. At that time we thought of our system as a translation of French intensive methods. We had replaced the heat-assisting methods of fermenting manure, glass-topped frames, and straw mats with our passive solar Pods constructed with modern materials. The improved heating function of our double-glazed, insulated devices, which trap sunlight and make its radiant heat available to plants even in the dead of winter, proved to be better and more versatile than traditional glass frames and cloches, which don't work in our cold climate because of their relatively poor insulation value.

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