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Cold Frames for Cold Weather Gardeners
Baby, it's cold outside, though admittedly "cold" along the Western coastline (the mountains are another story) lacks some of the fearsome implications that beleaguer the East — namely blizzards and icicles and snowplows. But still. It’s cold. And if it’s cold for you, it’s even colder for your garden plants, left to battle the elements outdoors. But surprisingly, winter is exactly the time when you should be preparing seedlings for the spring thaw — and a custom-built cold frame will help you in this endeavor.
Probably the very simplest thing to use as your frame is an old wooden window frame — especially if you still have the glass that fits it. If not, look for an equivalently sized sheet of plexiglass, or even plastic sheeting. Don’t have a window frame? Try an old tractor tire, a few two-by-fours, sunken cinderblocks, wooden fruit crates, or wax produce boxes. We’ve also heard tell of using a wire basket or milk crate wrapped in clear plastic and simply turned upside down. The basic idea is to have a solid enclosure covered with a clear, reflective surface.
Ideally it should be built on a slight incline to allow for better drainage, with either a southern or western exposure. Dig a shallow trench along the perimeter of the frame to anchor it — this will also help trap the heat. Rig your clear cover so that it can be raised on sunny days to prevent overheating, and lowered for nighttime/inclement weather. Keep an old quilt or space blanket on hand to throw over the frame on especially cold nights to keep the frost at bay.
Cold frames are good for lengthening the growing season of already-planted veggies (especially roots, lettuces, and leafy crucifers), warming the soil for early seed planting, and for providing seedlings started indoors with a protected environment for outdoor acclimation. Depending on the size and stability of your cold frame, you can choose to keep it as a permanent structure, or shift it around the garden to wherever it is needed the most. Either way, you’ll appreciate having some of the guesswork taken out of your spring planting, and your garden will appreciate the year-round attention.