Do-it-yourself carpenters who also enjoy organic, home grown herbs and vegetables can build a cold frame without the time and expense of a greenhouse. A cold frame is a transparent-roofed enclosure, built low to the ground, used to protect plants from cold weather. Inexpensive and easy to construct, a cold frame extends the growing season in most locations by a month or more.
Many of the lumber components can be recycled from one of your other projects. If you are using an existing window and frame for the lid, be sure to adjust the measurements below to the dimensions of the window.
The best woods to use for the cold frame are redwood, cedar or cypress wood. Here is a list of the materials and tools you will need:
Materials and Tools
- 1-4' x 8' sheet of plywood cut into 4-2' x 4' rectangles
- 4 corner anchors-2" x 2" x 2'
- Old 4' x 4'window or 4-2" x 2" x 4' wood strips with 45 degree miter cut ends and 4' x 4' fiberglass sheet
- 20-2" wood screws
- Drill with 3/8" bit (or whatever size screws you use)
- Screwdriver (cordless or hand-powered)
- Hammer
- 2" Nails
- Circular saw - if you cut the lumber yourself
- White, gloss oil paint and brush.
Building the Cold Frame
Arrange the 4 plywood rectangles to form a box 2' high by 4' wide by 4' long. Place the corner anchors on the inside corner and screw to the plywood sides. Paint the inside and outside of the box to reflect sunlight and protect the wood.
Move the box to an south-facing area that has unobstructed sunlight throughout the day during spring and fall months. Dig a trench for the sides of the box with the southernmost edge end deeper than the northern edge to create an angle. Spread the soil so it is higher in the back and lower in the front for optimum sun exposure.
Place a layer of well-rotted manure in the bottom and layer that with high quality, organic soil. Plant your seeds or sets, water and place the old window on top. If you don’t have an old window, drill holes around the perimeter of the fiberglass. Screw the miter cut 2"x 2" wood strips to make a frame. Finish the lid by screwing the fiberglass to the frame.
Place it on top of the cold frame. Add hinges if you want to swing the lid up for easy access to your garden.
Author Caryn Colgan grew up in a DIY home and has been a professional writer since 1984.
