Although greenhouses benefit the avid gardener or plant collector, it is necessary to take certain precautions during the winter to ensure that the plants are protected from frost. Even if you have a thermostat-controlled heating system in your greenhouse, you should set it up and maintain it correctly to cut back on heating bills. If cared for properly, you can have fresh vegetables, fruits or flowers year-round from your greenhouse.
Create a mixture of equal parts mild soap and water in a bucket. Thoroughly wipe down and clean all the surfaces within the greenhouse, such as the shelves, tables, walls and any surface where the sun shines through. Washing will cut back on dirt and other grime that blocks full sunlight from entering the greenhouse. It will also help the heat distribute more evenly.
Insulate the greenhouse to reduce on heating bills and to repel any critters or insects that try to seek shelter in your warm greenhouse. Use caulking to seal any cracks in the doors or walls.
Use an electric or gas heater to protect plants on the severely cold nights, placing them within proximity to pants to keep even temperatures. Keep a fan nearby to help distribute the heat source over the whole greenhouse.
Keep heat stored in your greenhouse from the sun by placing objects around that absorb the heat. This includes large containers of water, dirt or concrete floors, or full containers of soil set at the corners of the greenhouse.
Keep plants away from areas of the greenhouse that may have colder temperatures. For example, temperatures are colder towards the floor, so keep plants raised up in planter beds. This also goes for areas near the door or tight corners.