Soil Heating Cables
We are new users of a Greehouse. Last summer we built a 15 X 28' Greenhouse with tripple wall polycarbonate walls and roof. We decide to look at alturnative options (other than stoves/solar/gas) to heat our Greenhouse in the winter because of our cold climate (32 to -30 degrees during the winter) and the large cubic foot area of our Greehnouse (the ridge beams is 16' high). It would be hard for us to justify the cost of heating this Greenhouse for the amount of produce we want to grow for our own use over the winter months.
We came up with the idea of creating a hot box within our Greenhouse to grow vegtables over the winter. We have raised beds in our Greenhouse (36" high from the ground) 30"s deep. If we bury soil heat cables (with inline theramotates) in the raised beds about 6-8"s deep permantly and hinge a polycarbonate lid with sides over the section of the raised bed with soil heat cables - will the soil/air temperatures remain warm enough to grow cold weather vegtable crops like lettuce, carrots, radishes, spinach etc during worst winter months? We planned to have about 10" from the soil to the polycarbonate lid. We thought we would hang grow lights over the section of the soil heat cables for the short and dark winter days. We would also use the beds to start summer seedlings (like tomatoes) and then in the spring simply lift and leave the lids open during the growing months and use the beds as intented for summer growth.
We need the advice of experienced Greenhouse users in cold climates! Will this idea work? Has anyone tried this idea or do you have other ideas that may work for us? We would like to draw on your experience before trying this method. Any advice or ideas you can offer would be appreciated!