Pit Greenhouses or Walipinis. Depending on latitude, but despite above ground air temperatures (and wind chill), 6 to 8 feet down into the earth, temperatures remain fairly constant, between 50 and 60°F. Meaning your pit greenhouse will be much warmer than an above ground greenhouse in winter and that cool earth will keep temps bearable in the summer.
How To Build an Underground Greenhouse — Growing your own food isn't difficult in the summer, but winter gardening is a lot more complicated. It is made infinitely easier when you have a space that is insulated from the elements.