Wednesday, March 31, 2010
Urban Homesteading Part 3: Salads (almost) All Year
The south face of our house not only helps heat the interior of the house on cold but sunny winter days, it also heats anything on the outside of the house. I first saw a "cold frame" about three years ago at Three Sister's Permaculture Farm in Sandy Lake, PA. This is Darrell Frey's farm and the location of his bioshelter, a large passive solar green house which incorporates compost and chicken manure into the fertilizing and heating of the building. On the outside of the bioshelter are about a dozen large cold frames. We were there in March with snow on the ground the first time we visited. The inside of the bioshelter was warm and teeming with salad greens, nasturtiums, and herbs, which had all not only survived the winter, but thrived through it. The remarkable aspect of this place is that the bioshelter uses NO natural gas, electricity or any other fossil fuel for heat. Only compost, the sun, and on the coldest nights - firewood. Most people, including myself for a long time, don't realize the enormous amount of fuel needed to heat conventional greenhouses through the winter. That's why so few farmers use greenhouses for growing veggies all winter long. It can be done, but costs way too much money, not to mention the greenhouse gasses produced in the environment. As we walked around the bioshelter and heard about how it was made 25 or so years ago we asked about the cold frames. Darrell opened one up and, lo and behold, a lone mustard green plant. Darrell didn't even know it was in there. It had survived the winter with absolutely no care, only the shelter of a window facing the sun. My friend Lance and I both took a leaf and ate our first fresh garden-green of that spring. It seemed amazing that something could survive the winter with no care. In reality, this is the easiest way to grow salad greens almost all year round.
Our cold frame is a bit small, about four feet by four feet. I used scrap lumber from my garage and from Construction Junction and a $10 used double paned window from the same store. I then attached hinges to open and close the window at the top of the frame. It's very important that your cold frame have an easy way to be propped open too, the sun can quickly raise the temperature too high for your plants, especially in spring. The sides of the frame should slant downward toward the sun to allow as much sunlight in as possible. The rear of the frame should be at least one foot high and the front can be only a few inches off the ground. I used weather stripping around the frame where the window closes against the wood.
We built our cold frame a little late in the season last year, late October. It's a bit difficult to get greens growing that late in the season. But, by December the greens were ready to begin harvesting. We used a few different salad green mixes and some of those hardy mustard greens. I was sure that everything was completely dead and frozen during the single digit nights of January and February, the plants all looked wilted and frozen. But, as soon as a warmer day with sun came, they all perked back up! We didn't eat much from the cold frame in January and early February, but allowed what had grown in November to survive and provide for our salads in late February, March and April. I've been cooking the larger kales and Boc Choi as well as feeding lots to the chickens, who were so excited to have fresh salad greens in February and early March, before the grass started growing.
A cold frame is super easy to build. It's fun to go outside on a cold late February day and pick salad greens like it's mid May. A larger cold frame would be better for our family, I'd recommend maybe 4x6 or 4x8 with two 4x4 windows. All you really need to put in a cold frame is a side of your house that gets lots of sun, building it is the easy part.