Building a cold frame was last weekend’s project at our house and we did it in the nick of time, just before the cold blast of arctic air and many inches of snow hit us this week.
Although we built a winter greens hoop garden a few years ago and it is working to produce winter greens like a charm (see my post about that here), my goal was to do a fall gardening project using the salvaged glass I’d saved years ago to make a cold frame.
Being in town, unfortunately, our neighbor to the south has a lot full of huge overgrown trees which shade our house in the wintertime, therefore my chosen “best” spot site for this mini-greenhouse isn’t perfect, but will get a few hours a day of sunlight on sunny winter days. The spot happens to be sandwiched between the concrete driveway and the house.
First, we took a trip to a neighbor’s dumpster where they are deconstructing part of a house and picked up a couple pieces of wood there, and then, we headed to our fabulous Boulder Resource Center (recycled community materials) to look around. It was a lucky day there, because we found three perfect sized lengths of redwood which ended up being exactly what we needed for the project.
The first photo, below, shows the project in its early stages. Designing the box with the materials at hand was the hardest part and I took a great deal of care and time in the planning stage. To construct it, my husband did the sawing and I got to have fun using the electric screwdriver.
This photo shows the project farther along, with glass in place. Careful measuring has paid off nicely.
Finally, the box is in place. Since this photo was taken, I’ve sunk it’s edges into the ground, found an old thermometer to put inside, and started a few spinach seeds as an experiment. I stacked rows of bricks against the back wall and plan to place a few old milk cartons inside that are filled with water as additional heat sinks. The floor is already covered in small rocks which should also help retain heat for this passive solar mini-greenhouse.
It seems to be pretty well settled that the plastic hoop house works best for growing winter greens in our area and if you think about it, glass conducts cold a lot better than plastic does. Eliot Coleman layers plastic with success in Maine’s cold winters. My project is an experiment and I hope to try a few things but mostly I want it for starting seeds next spring. I already think I should have made it taller so it could house some short tomatoes, but I will work with what I have. The glass panes slide apart nicely to vent it when it gets too hot inside and I will either bring the cold-sensitive seed starts indoors or throw a blanket over the frame on the colder spring nights.
Whew. Got it finished just in time. The total cost was about six bucks for this salvaged-materials project.
NOTE: As I post this, the outdoor temperature is 27F and the cold frame’s thermometer is showing 85F after the sun hit it an hour ago. Later… 100. Wow.
Also recommended, this previous post: Extend Your Growing Season with Simple Backyard Coldframes or Hoop Gardens.