At this time of year, in my neck of the woods, people engage in bizarre bragging rights. We take pleasure in bragging about who has the most snow, coldest temperatures, and worst forecast. (BTW, it's currently a balmy 30 degrees with a foot of snow on the ground in my neighborhood.) But wouldn't it be great if instead we were bragging about who had the most salad greens and radishes growing in their garden? With a DIY cold frame you can keep your garden growing year round no matter the weather.
Why a cold frame?
A cold frame allows you to extend your growing season. Depending on how sturdy your cold frame is, you may be able to garden year round. True, you won't be able to grow tomatoes in your cold frame, but salad greens, spinach, scallions, and carrots will fare well in one.
- A top for the cold frame: This will be something that sunlight can penetrate. I used a recycled window--without lead paint--with glass found at a yard sale or recycling center. I've heard of folks using old shower doors as well. Alternately, acrylic or fiberglass sheets sandwiched between thin wood boards will work.
- Non-decomposting wood for the frame: Cedar or cypress are fine choices. Avoid any wood that has been treated such as pressure-treated wood. Boards shouldn't be wider than 1 1/2 feet. You want to be able to easily reach all areas of the cold frame garden so don't use boards longer than three or four feet.
- Hammer and nails/drill and screws for assembling the frame.
- Heavy duty hinges.
- A prop (i.e. sturdy stick or board) for ventilation.
- Soil and seeds.
Build a cold frame in 5 steps
1. Select a location. Ideally, this will be a south facing location as you want as much sun as possible. However, in warmer climates direct southern exposure might be too hot, so consider a location that gets slightly less sun or morning sun versus afternoon sun.
2. Build the frame. I'm not known for my woodworking skills (yes, I flunked seventh grade shop class) but I am able to cut boards to length and hammer nails somewhat straight. If you're lucky enough to know someone with serious wood joinery skills then offer them a trade of their labor for fresh veggies.
3. Attach the hinges to the back of the frame so that your top will be able to open and close.
Note: If building a frame and attaching hinges isn't for you, then there are other options. Use hay or straw bales for the sides of the cold frame and simply rest the top on them. Cinder blocks are also a good choice for sides. If you choose either of these options be sure to choose a top that isn't too heavy because you'll need to lift it on and off to tend the plants inside.
4. Prepare soil. Blend a nutrient rich soil composed of compost, peat moss, and top soil.
5. Plant! Cold weather plants will grow best. Try arugula, beets, broccoli, cabbage, collards, chard, kale, and kohlrabi.
A cold frame isn't only for planting. Use the sheltered space to help tender plants over-winter. In the spring, use it to start and harden off seedlings before they go in your garden.