Greenhouses located in residential areas can take advantage of their proximity to a nearby power grid to power electrical heating systems to keep their tender plants warm in winter. But for greenhouse owners with greenhouses located in remote areas, the choices for growing plants are more limited. And while all greenhouses heat with solar radiation during the day, once the sun sets, greenhouse owners will have to be more creative to heat their greenhouses.
Dig a trench in the ground down the center of your greenhouse. This trench must be at least 3 feet deep by 3 feet wide.
Fill the trench 1/3 full with sawdust.
Add a 1-foot deep layer of manure over the sawdust.
Top off the trench with another 1-foot layer of sawdust.
Water the sawdust and manure mixture until it is as wet as a wrung-out sponge. Check the internal temperature of the compost mixture with a compost thermometer. The temperature should rise to between 130 degrees and 150 degrees. Stir the mixture any time the temperature drops below 130. The compost will heat the greenhouse as it decomposes, and the finished compost can be used in your greenhouse.
Place a black rain barrel full of water at each corner of the trench and cover with a piece of 3/4-inch particle board to create a table for your plants. The rain barrels will absorb solar heat during the day and release it at night to warm the greenhouse.
Cover tender plants with a layer of bubble wrap during unexpected cold weather to create a second layer of thermal radiation and warm the environment under the bubble wrap by one climate zone.