A SEED-STARTING SOLAR COLD FRAME

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The glazing adds additional stiffening to the lid assembly, and both of the 19-1/2" X 50" sheets and the 4" X 50" ridge cap can be cut from a single 10' piece of corrugated translucent fiberglass. Attach the sheets to the ripple board by drilling 1/8" holes in the material and sinking No. 6 X 1/2" sheet metal screws — fitted with rubber washers from aluminum roofing nails — into the openings. Then pop-rivet the fiberglass cap over the joint between the two sheets at the peak of the roof and seal each fastener with a dab of silicone caulk. (See the illustration for placement of rivets and screws.) An additional application of sealant between the ripple board and the fiberglass, and along the seam where the material contacts the horizontal 1 X 2's, will help to retain heat. To close in the ends of the cold frame's lid, cut out two 18" X 18" X 25" triangles of 3M Flexigard (or a similar material) and staple the plastic — spacing the fasteners three inches apart — to the ends of the frame.

Though you could simply set the lid atop the box, we decided that a trio of hinges and a handle would provide a more convenient arrangement for opening the cold frame during the heat of the day. Three standard hinges were attached to the outside of the insulation box and the 1 X 2 on the frame, and the 1-1/2" screws and nuts were backed (on the inside of the box) with 2" X 3" pieces of 1/8" plywood. On the other side of the lid, we fastened a 1 " X 8" chunk of leather to the 1 X 2, using panhead screws, to serve as a handle.

To put the cold frame to work, simply prepare a 25" X 48" hole that's 6" deep, cut three 1" holes in the bottom of the box for drainage, and set it into the pit. Then open the lid and fill the container with about five inches of a combination of the earth that was removed from the hole and whatever fertile soil you prefer. With the ground and insulation preserving a favorable environment for growing and the sun beaming down in the daytime, you should be able to start seeds safely three weeks before the last frost predicted by your agricultural extension office. And once the final freezing chill has passed, you can set out thriving seedlings in your garden . . . ready to resist pests and grow their way toward your dinner plate!

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