The science behind greenhouse heating systems is to trap air and light. They are made to preserve off-season fruits and vegetables by managing temperature. While greenhouses absorb heat, they need help keeping warm during the colder months, and here’s what you need to do.A greenhouse needs appropriate ventilation and direct sunlight exposure. It is crucial to know how to keep a greenhouse warm in winter. You can do this by harnessing the force of nature and heating a small greenhouse.