Toward the end of the season the husband finished building us a cold frame box. I tried to find the directions we used but he did modify them quite a bit. If you search for “cold frame box” online you will find a variety of resources, pictures and plans. He made ours from scratch using cedar, some hinges, a handle, a vent for air flow and some plexiglass.
Cold Frame Lettuce Box
Many plans call for using an old window or glass door for the lid. Many plans also suggest making your cold frame about the size of a door. Ours is more of a square shape, but probably equally large. However, you can also make a cold frame smaller if you have less space outside. If possible, the cold frame box should be placed facing south. The way a cold frame works is it’s like a miniature greenhouse. Here’s a look inside.
The sun hits the angled lid and it produces heat inside the box to keep crops growing well past the normal gardening season. A cold frame is especially helpful for those in regions where winter hits hard — ie. Cleveland. Normally gardening season is wrapping up in October. But today is December 10 and I’m still picking fresh lettuce outside!
I’m really not sure how long the cold frame will keep the lettuce growing and I’m almost certain I cannot plant any new seeds at this point. If we had finished the frame sooner I would have planted some broccoli in there too. Another disclaimer, I’m new to growing lettuce so I don’t know how long the lettuce keeps growing. I’m assuming as long as I pick it but I’m also thinking it might get bitter and past it’s prime eventually.
If you know or have used a cold frame, please chime in!