To obtain the first crop of vegetables in a greenhouse, a certain air temperature must be maintained. The Lezhebok heat accumulator, which is a sleeve made of black polyethylene, will help in this. Water is poured into it. During the day, the battery heats up, and at night it slowly gives off heat, raising the air temperature in the greenhouse. It is easy to use, inexpensive, and the effectiveness can be estimated by reviews of the heat accumulator for Lezhebok greenhouses.