Cold frames have been used to grow vegetables in winter since glass was invented. Winter gardening is made possible with cold frames and hoop houses. Using a recycled window, we built a cold frame last year - see our how to build a cold frame video here - and had good success growing vegetables in the winter and starting plants early in the spring using the cold frame.
This year I took volunteer plants that had sprung up around the garden: Mustard Greens, Swiss Chard, Garlic, Chives, and parsley and transplanted these plants into the cold frame. These plants all do well in colder weather, so we'll have some nice greens for salads in the middle of winter. How cool is that?
The key to using a cold frame to grow vegetables is controlling the temperature inside the cold frame. We use an automatic vent that has louvers that open at about 45F, letting hot air out of the cold frame. It is called a crawlspace vent at the hardware store. You can buy the automatic vent online here.
The recycled window we used is a single glaze, meaning it has only one sheet of glass, you can also use double glazed windows. As we say at GardenFork: Use what you got.
You can make a larger cold frame, aka a plastic hoop house greenhouse, by watching our hoop house video here.
Let us know your cold frame and hoop house tips and suggestions below, thx, eric.