I’ve mentioned a couple times that we are gearing up for our first foray into fall and winter gardening. One of the most valuable tools for fall and winter gardening is the cold frame.
A cold frame is essentially an unheated bottomless box with a glass or hard plastic hinged lid that is placed over an area of soil. Plants are grown inside the box. The glass or plastic allows light into the box, so the inside of the box will be warmer than the outside temperature. In the case of winter gardening, the enclosed structure of the cold frame also protects the plants from snow.
Eliot Coleman teaches that for fall/winter gardening, the plants are started in late summer/early fall, and are more or less full grown by November 15. After this point they won’t grow much further. By protecting them in a cold frame, you allow the plants to hibernate during the winter. They don’t grow substantially, but they aren’t destroyed by the elements. They’re basically placed in extended cold storage.
We followed Eliot’s general guidelines for building the cold frames and built them out of cedar. Cedar is naturally rot-resistant, which means that the wood doesn’t need to be treated. Since the frames will be in contact with our soil and potentially our food, I didn’t want to use any sort of wood varnish or preservative. We built the boxes to be 44×44″, so they will just fit inside our garden beds and we’ll be able to have four frames side by side within one bed. The back wall is 12″ tall and the front wall is 8″.
We are going to go the hard plastic route for the glazing rather than glass because I’m paranoid of breaking them. We haven’t purchased the plastic yet, but I’m really happy about the progress we made in just a few hours on a Sunday.