Growing Guides · 6 min read
A Cold Frame From the Scrap Pile
One sheet of polycarbonate, some pallet boards, and six weeks of December salad.
A cold frame is a cheap greenhouse with attitude. Ours costs one sheet of polycarbonate, a stack of pallet boards, and an afternoon with the good screwdriver.
What you need
- One polycarbonate or old-window lid, at least 3 by 4 feet.
- Pallet boards for the back (18 in) and front (12 in) walls, on a slope facing south.
- Hinges, four screws per corner, and a brick for the hot afternoons.
What it does
The slope buys you about eight degrees over open ground, which converts September sowings into December salad. Sow lettuce, spinach, and claytonia in early September, close the lid by late October, and vent it with the brick whenever the sun is out. The rule at the bench: if you would want the window open, so does the frame.
“The frame fails closed in two ways: forgotten venting cooks the crop, forgotten latch invites the wind. Choose the latch.”
By March the frame is warm enough for the earliest sowings, which is when it starts its second career as a seedling nursery for the whole garden. One frame, two jobs, and the pallets were free.