Its a protective covering for plants, or can be used to warm soil before planting, usually tunnel shaped, rigid and come in all sizes....

You can also get bell-shaped plastic cloches in several sizes - to protect plants from the cold.

Anything that will let sun light in and keep cold and wind out is a cloche. They can be any shape and size and are one of the gardeners best tools for bringing on both flower and food plants!

Its a kind of coat for plants, not as daft as it sounds. There are so many kinds. You can make your own by cutting the bottom off a large drinks bottle and putting it carefully over your plants in the garden. They hold in heat, protect plants from the wind,heavy rain and slugs