With fall nearly upon us, the night temperatures have dipped to close to 50 degrees for a few nights. This is the time when our family starts to mourn the end of our bountiful garden season, as many plants are just not very happy when the temperatures dip that low (think tomatoes, basil, squash, and many types of annual flowers). We are still planning on enjoying the fall crops that continue to do well despite the first signs of frost (many greens, broccoli and its cousins, for example), but are we ready to give up our gardening hobby already?
The answer our family came up with this year was, “no way!”. We are just having to much fun! We did a lot of research about greenhouses (the kind that are heated and allow for an all-year growing season), and came up dismayed at the prices and work involved in what is really a serious building project. Our answer and compromise was an inexpensive “cold frame kit” (which by the way was marketed as a “greenhouse”, but in my mind a greenhouse is something that is a permanent structure instead of our temporary one). A cold frame does not have a heat source, and can be set up as a separate area in your yard or can actually be set up over your existing planting beds (see photo A, not our project).
How a does a cold frame work? They trap heat by admitting sunlight in during the day through its covering and retaining heat radiated from the surrounding soil during the cold night hours. When closed, it also traps moisture inside the structure cutting down on your watering chores. The idea is that you can keep the temperatures inside a cold frame about 5-15 degrees warmer than the outside. That difference may not seem like a lot, but we decided for the ease of the project (and how relatively inexpensive it was), we would try an experiment this year. Our cold frame consists of a metal frame with a Polyethylene Film cover (see photo B). We put this kit together in about 6 hours, but that involved a lot of breaks and distractions with the kids. They loved sorting the pieces, and they couldn’t believe what we were putting together would end up a 6 X 10 “house”! Once the frame was up, we simply pulled the polyethylene film (which is basically a clear tarp with some insulating power) over the top and down the sides and secured it. Here was what we planted (started around Labor Day) so that the plants would be somewhat established before the weather gets to cold: spinach, tatsoi (an amazing oriental green), swiss chard, beets, carrots, and various types of lettuce. We’ll let you know how it goes!
Do you have any tips for extending the growing season? Please post a comment and let us know!