The Future is Abundant
A Guide to Sustainable Agriculture

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Extending the Season

Vegetables and herbs fresh from the garden make a wonderful winter or early spring salad. Some are relatively easy to grow. Siberian kale is as hearty as it is rugged. Corn salad make a perfect complement and, depending on your climate, can be grown with little or no protection.

Extending the growing season is a challenge that is amply rewarded, and does not necessarily require fancy or expensive protection devices. Many salad greens besides those mentioned above can be kept growing throughout the winter and spring with simple cold frames or portable coverings called cloches.

"Cloche is a French word for bell. Cloches, or "bell glasses," were an essential part of French intensive gardening. First introduced in the 17th century, bell-shaped jars of blown glass were set over plants in the garden to extend the growing season in the fall or to force lettuce in early spring. Use of the term cloche has since expanded to cover a wide variety of temporary structures that can be put over plants in the garden,\ opened to allow for ventilation, and then removed when no longer needed.

Unlike a greenhouse, in which you create an artificial environment, the idea of a cloche is to work with nature, creating a warm micro-climate right around the plants in the garden. The difference between a cloche and a cold frame is that the cold frame is usually a permanent structure while cloches are temporary and portable.

A simple modern equivalent of the traditional French bell-jar is a one-gallon clear plastic or glass jug with the top or bottom cut out. These jugs can serve as hot caps over tender young plants. Air circulation is essential. To allow for proper circulation, either prop open or remove the cloches on sunny days and then replace them at night.

In May 1980, the Seattle Tilth chapter received a $5,000 grant for a coldframe and cloche demonstration project. In his article "Cold Frames and the Year-Round Gardener" (Tilth, Vol. 7, No. 3), project coordinator Carl Woestendiek described some varieties of lettuce and Oriental greens which were most successful in the structures he built. His article makes the point usually stressed in discussions of extending the season--that the proper choice of varieties can mean the difference between success and failure. Excerpts from Carl's article follow.

Of the Oriental greens, the Green Wave, Mizuna, Florida Broad Leaf and Chinese Broad Leaf have the most satisfactory growth. Tendergreen mustard tended to bolt readily in the lengthening days after the winter. Still later in the season Mizuna mustard showed some tendency to bolt, but was valued highly until then for its mild flavor and attractive appearance. The edible chrysanthemum, though not as fast growing as the mustards, did grow at a reasonable pace and was valued for its unusual flavor. Chinese Broad Leaf and Florida Broad Leaf mustards were the most spectacular in their rate of growth, and the Green Wave mustard was the most resistant to bolting.
Winter Density was the only romaine-type among the lettuces. All-Year-Round, Winter Marvel and Arctic King are all Bibb types, and of these, All-Year-Round was both the fastest growing and least cold hardy.

The most destructive pest in the frame and cloche plantings was the slug. Warmer winter outside temperatures coupled with the warmth of frame and cloche served to increase their numbers. The broad leaf mustards with some hair on their leaves (Florida Broad Leaf, Chinese Broad Leaf and Green Wave) showed the least slug damage.

The Future is Abundant A Guide to Sustainable Agriculture

Extending the Season

The Future is Abundant
A Guide to Sustainable Agriculture