I'm working on a way to start seeds and grow greens in the winter without building a full-blown greenhouse, and I was wondering if anyone around here has done something similar and would care to share their experiences or ideas. Basically, I'm going to build a big insulated box, put a rocket stove in it, fill around the stove with sand and gravel, and then put a box of seeds to start on the top under a glass lid. It's like a heated cold frame with a large thermal mass, or a rocket bench where the butts are replaced by plants. If it works I might build a big long one and use it for growing greens and herbs through the winter.
It's kind of hard to see in the image, but there is a damper between the exhaust line and the plant box so it can be shut off. The main exhaust runs out the side of the box. I'm not sure it's a good idea to have the pipe running up there to the plants at all actually, but I thought it might be a good option to open it up on a super frosty night to let more of the stored heat in.
I'm hoping I can keep the plants nice and warm during our sometimes bitterly cold weather so I can get an early start on the garden this spring. Any thoughts?