Depending on your climate, the design of your greenhouse, and the types of plants you intend to grow, a simple air source geothermal system may be ideal. These systems are easy to build, require little to no maintenance, and provide enough warmth to keep your well-insulated greenhouse well above freezing even on the coldest nights.
In colder climates, or when working with sensitive seedlings or tropical plants, you may choose to add supplemental heat in case of a particularly severe cold snap. Fortunately, heat pumps operate much more efficiently and cheaply when connected to a geothermal heating system.
