Cold Frames for winter veggies
Unless you live in Antarctica you can probably grow things in a cold frame. We’ve used one the last two years. I cannot claim to be an expert, but here is what we’ve learned.
- Our research taught us to put the cold frame on the south side of the house. The sun is on a lower arc and travels across the south side of the sky so this way you get more sun and less shade. The deciduous tree reflected in the glass actually shades this bed in the summer or it gets too hot because the light-colored siding reflects onto the bed but in the winter that reflected heat is a plus.
- We opted for a simple cold frame of used window sashes and foam insulation board walls. We assemble it on top of the raised bed in the winter and store the sashes and cut foam the rest of the year. Any gaps in the insulation are taken care of with slit foam pipe insulation. And the bed is mulched, which not only holds in water but helps insulate it. Total one-time cost, about $38.
- Using a cold frame means keeping an eye on the weather forecast! If you leave the glass in place on a warm day you’ll cook the vegetables. If you leave it open on a below-freezing day, they’ll die of the cold. If you don’t water the things inside they can wilt, although that takes a while in cool temperatures. When it gets into the 20s (degrees F) we plug in an incandescent light bulb which heats the space. If it gets into the teens or below we throw old quilts over it at night.
- What do we grow in our cold frame? All of our late lettuces get transplanted into the back; this year it’s Jerhico cos which we pluck from the top both to keep it from bolting and to keep it below the glass where it might freeze. Last year it was that and black seeded Simpson leaf lettuce which we may still grow from seed out there. We’ve put beets for green seedlings in the front since they are not as tall, which also gives them a head start in the spring. The last of the late cabbages are being allowed to mature one end. Last year we left carrots in the ground in the cold frame so they could make seeds the 2nd year.
Since we also have kale and leeks out where the frost will make them sweet in the main garden, that’s enough. It’s supplemented with pickled and frozen and canned vegetables but it’s nice to have fresh greens.