I have a friend who is teaching me gardening. One of the things I have learned is storing potatoes, carrots onions ect in an old broken freezer or refrigerator. We got one free and put it in the barn. It will hold 3-4 hundred pounds of vegetables and keep them from freezing. You get a electric thermostat and set it to come on at 34 degrees and go off at 38. This operates the light for heat and keeps the vegetables from freezing when it is very cold. Most of the time it does not come on. My mentor has done this for 20 years and only had the light come on last year when we had several weeks of temps in the teens. He stores his stuff all winter in this manner and has not lost anything. Effectively this is a portable root cellar.