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Kristi Hendricks

Gardening under glass has a rather elegant ring to the practice. But the time-honored use of cloches was originally concocted for practical reasons. In case you aren’t familiar with this gardening term, the word cloche is French for bell, as in a bell-shaped jar. The home gardener can extend the growing season by sheltering plants from cold temperatures in these domed, translucent coverings in autumn, winter and early spring.

Such plant protectors were designed to cover just one plant of value in a mini-greenhouse environment, free from frost and damaging winds. Cloches trap heat and moisture in at night, assisting seeds to germinate, seedlings to develop adequate root systems and vegetables to bear earlier in spring.

As usual with horticulture activities, history plays a role. The use of cloches dates back some 400 years. French, English and Dutch gardeners readily adopted the use of cloches. Naturally, the practice spread to the New World. Before the American Revolution, early colonists were known to use bell jars in winter for frost protection for small plants such as broccoli and cauliflower, which are less cold-hardy than the rugged cabbage.

Bell jars were known to convey the economic status of the gardener. If clear glass, the protective covering was imported and expensive. If a lightly-colored green, the cloches were made locally. Honeybee skeps were often used if glass was deemed too costly. Later, gardeners used Mason jars or repurposed other glass jars.

It is known through his extensive horticultural writings that Thomas Jefferson utilized cloches in his elaborate, terraced vegetable gardens at Monticello. Glass cloches are still displayed in today’s historic gardens to add an atmosphere of authenticity.

The glass knob on top of the cloche evolved later than the bell, improving handling and lifting but magnifying the sun’s rays. Most knobs were removed due to plant scorch. Temperatures under a cover can quickly grow too hot for plants. The smaller the cloche the faster the temperature will warm up inside. Remove or ventilate cloches on sunny or mild days.

Instead of protecting an entire field of plants with cloches, commercial growers now deploy row covers. Home gardeners have gravitated to cloches made of plastic or the wax-paper hot cap. Windowpane-like glass and wooden frames are also popular for extending the planting season. The frames can be “hot” or “cold” depending on whether they contain manure (hot) or not (cold), but both provide protection.

See VCE publication 426-381 for additional season extenders.

 

KRISTI HENDRICKS is a member of the Western Tidewater Master Gardeners. Contact her at GardenontheJames@yahoo.com.