Create a Cold Frame for Your Garden
Get a head start on spring planting with this DIY cold frame.
Spring can’t get here soon enough. Garden planned, seeds purchased and a trowel at the ready. Waiting for that frost date to arrive is an exercise in patience. Sudden temperature swings in the North Carolina piedmont are not uncommon and planting in the garden prematurely can devastate a crop before it has even begun. Building a cold frame allows the intrepid gardener to get a head start with spring planting without risking late-frost disaster.
Kind of a mini-greenhouse, a cold frame at its simplest is an enclosed bay with a clear top that will allow sunlight in and trap heat. It requires attention, making sure temperature and moisture are appropriate, venting as necessary. But a cold frame is a terrific way to beat the limitations of the growing season, adding valuable weeks for the development of young plants.
Get a jump on spring planting using found or inexpensive materials. Visit the gallery below to learn how to build your own cold frame.
Protect Your Plants With a Cold Frame
Get an early start on spring planting or extend your gardening season with this DIY cold frame. A type of “mini-greenhouse,” a cold frame built with a glass or plastic lid allows plants access to sunlight and traps heat to prevent cold weather from putting an early end to your new crops. Follow these simple steps to construct your own cold frame using just a few tools, lumber, and a reclaimed window frame. The addition of a temperature-sensitive foundation vent will keep air flowing without risking plant loss due to unexpected cold snaps.
Tools and Materials
You will need: reclaimed 24-inch x 48-inch window (check window replacement shops, thrift and antique stores) / 2-inch x 8-inch x 16-foot rough cedar plank / one foundation vent / twelve 4 1/2-inch lag screws / two 3 1/2-inch galvanized T hinges / 8 hinge screws / two 4-inch eye hook latches / tape measure / drill with pilot bit and screwdriver tip / circular saw / straightedge / c clamps / jigsaw
Measure and Cut Lumber
From cedar planks, measure and cut three 48-inch lengths, two 18-inch lengths and one 20-inch length. These will be used to construct a simple raised bed and a second-tier angled cap to which the hinged-lid window frame will be attached. This project uses a 24-inch x 48-inch reclaimed window, but may be adjusted to accommodate windows as large as a storm door by matching the box size to window size. A larger cold frame may benefit from the addition of a second vent.
Measuring 1 inch from the long side of the two 48-inch planks, drill a hole at each marked point 3/4 inches from the short edge using a pilot drill bit. Using eight 4 1/2-inch lag screws (two at each corner), assemble bed by driving screws through prepared holes into two 18-inch sides to form a rectangular box. Make sure all corners are square and don't overlap.
Assemble Window Mount
Mark a spot 1 inch from the top and bottom on the back of the second tier at each end, then drill a hole at each of the four marks 3/4 inches from the end using pilot bit. Attach the angled sides to the back of the second tier using 4 1/2-inch lag screws driven through the pilot holes you have made.
Measure Placement for Foundation Vent
On the back of the cold frame, use a straightedge to mark a horizontal 8-inch x 15-inch rectangle with sides centered horizontally and two inches from the top edge for the foundation vent. The addition of a foundation vent will allow air to circulate during warm period and trap heat when temperatures drop below 40 degrees F.
Attach Hood and Eye Latches
At the midway point, drill pilot holes to attach 4-inch hooks and eye latches inside the frame at each end. The latches will hold the top and bottom tiers together when in use, but allows for easy disassembly. Window latches may also be used instead, if desired. With the lid removed, the bottom tier may be used as a raised bed during summer months and the lid stored until cold weather returns.
Insert Foundation Vent Into Frame
Push the foundation vent into the prepared hole until it snaps into place. The passive vent will automatically open during warm weather and close when temperatures drop below 40 degrees F. A 30-inch dowel can be used to prop the lid open to take full advantage of warm weather and maximize air circulation, but this vent is an invaluable fail-safe.