Arney, that would likely depend on where you live. Frost lines, at least here in New England, RARELY extend beyond the first 6" of earth. Once you get through that, the ground is no longer frozen. But, our root cellars here are actual cellars; in MA, a house is required to have a basement as part of the building code, with a couple exceptions (apt buildings & modular homes being two of them). Most older homes have basements with packed dirt floors-houses built, say, before the 50's. Granted, most folks these days likely pave it over with cement, to finish it, but I recall the house I grew up in having packed earth floors, and my feet ALWAYS being dirty-getting yelled at for tracking dirt from the cellar through the rest of the house was a daily occurence!