Harnessing the Sun for Year-Round Garden Produce

SOLAR GARDENING: GROWING VEGETABLES YEAR-ROUND THE AMERICAN INTENSIVE WAY By Leandre Poisson and Gretchen Vogel Poisson; Chelsea Green Publishing Co., 267 pp., $24.95 paper.

MORE than 20 years ago, Leandre and Gretchen Poisson cleared a small opening in the New Hampshire forest and started a garden. So began an unwavering commitment to self-sufficient living.

They wanted to raise their own food in the most energy-efficient way possible. That they succeeded, where so many in the back-to-the-land movement of the early 1970s failed, is borne out in the highly productive system of horticulture they developed called American Intensive Gardening. And while this system, which emphasizes solar energy, was developed on a one-eighth acre garden plot, its principles apply to all sized operations, from the tiny suburban garden to commercial vegetable operations.

``Solar Gardening: Growing Vegetables Year-Round the American Intensive Way,'' the Poissons' book, explains how the system evolved and how it can be applied wherever the reader may live.

To understand the Poissons' approach to gardening, we need to appreciate their concern with what they term ``net energy gain.'' By that, they mean that the energy content of food from the garden has to exceed the energy contained in the fuels, fertilizers, and other products used to grow that food. (By contrast, mechanized agriculture consumes 25 times more energy than it produces in corn, wheat, and other crops.)

Their other goal was to grow food - even in the snow-covered winter landscape of New England - year round.

In tracing the evolution of American Intensive Gardening, the book follows the Poissons' discoveries, experiments, and garden innovations. ``Each leap in understanding that we made fueled our curiosity and spurred us on to do even more research,'' they write. In the end, they achieved their goals, and while few readers would be as dedicated to self-reliance as the Poissons, the principles employed would interest every serious gardner.

The Poissons' search for answers began by looking into the works of Helen and Scott Nearing, pioneers of self-sufficiency in the United States. They also researched the intensive-bed practices of indigenous cultures in Central America. But it was the use of glass-covered hot beds by French intensive gardeners around Paris in the 19th century that most interested the Poissons. To grow food year round without resorting to the heavy energy costs of conventional greenhouse culture, the effective harnessing of solar energy was vital.

What they learned became the springboard that launched them into their own discoveries. The end result is a readily sustainable, year-round food-growing system that includes solar devices developed by Mr. Poisson. A designer and architect by training, he calls them garden ``appliances'' because they lighten the garden workload the way kitchen and other appliances improve the indoor work environment.

They include the readily made Solar Cone, for jump-starting the spring season and adding several weeks of additional growing time in the fall, and the more substantial Solar Pod, a greenhouse in miniature, that makes year-round production possible. The Solar Pod, for instance, can almost double the growing season even for frost-tender crops like peppers from 16 weeks in New Hampshire to 30 weeks, while kale, among the cold-tolerant crops, can survive year round. Construction plans for all solar appliances are included in the book.

The book also deals with siting and soil building, along with tips for growing more than 90 garden crops, conveniently grouped into heat-loving, cool-hardy, and cold-tolerant species.

``Solar Gardening'' is aimed at the serious food gardener, but doesn't require that the gardener be experienced. A newcomer with serious intentions would also enjoy this easy read.