(COVER), cold frame [noun] [C] - a piece of clear material, sometimes on a frame, which can be used to cover plants for a short time, esp. in order to help them grow faster or to protect them from very cold weatherThis early variety of lettuce grows well if protected by a cloche until the weather warms up.
CLOCHE
Meaning of CLOCHE in English
Cambridge English vocab. Кембриджский английский словарь. 2012