Cloches and miniature greenhouses

The French developed the glass cloche, or bell jar, in the eighteenth century, it was formed from a solid piece of glass shaped like a dome and intended to protect an early garden plant from cold and frost, hastening the plant to maturity or protecting tender blooms such as camellias from weather damage.

The Dutch and English expanded this idea with larger and less movable plant protectors which were lantern shaped, faceted pyramidal covers that combined glass panes and frames of cast iron or even lead.

These two designs have undergone a sudden resurgence, less for their plant protecting value then their ornamental one. They look lovely in the garden and, like hanging lanterns, trugs and other heritage items, they’ve become accessories of choice for the fashionable gardener.

However, they have a serious cultivation purpose too, by setting up small, inexpensive season extenders you can stretch the harvest of summer crops into autumn, keep autumn crops actively growing through mild winter weather, and help plants get a good start in the spring. Cloches can protect plants from moderate frosts and increase daytime temperatures by 5-20 degrees.

Cold frames are more like miniature greenhouses; with wood or stone sides, and glass or rigid plastic glazing on top. They provide more protection for plants since the sides are solid, and are generally more permanent, often they are built onto the side of the house to provide extra shelter and their glass or plastic roof may be removable in summer and replaced with mesh screens.