How to Build a Cold Frame

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Start seedlings in a cold frame while temperatures are still too low for planting directly outdoors.
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“Organic Gardening Techniques” by Nick Hamilton, is filled with expert gardening tips to help gardeners of all skill levels.

Organic Gardening Techniques(Companion House Books, 2018) by Nick Hamilton, offers gardeners insight for planting and growing various fruits, vegetable and herbs. Find your gardening niche with help from Hamilton and see how your gardens can blossom. This excerpt can be located in Chapter 6, “DIY Projects for Your Garden.”

Cold frames are relatively easy to make, and this is a far cheaper option than buying a similar-quality product. All that is required to make one is rough-sawn lumber in the following sizes and a few tools.


  • Size varies according to your requirement but usually no more than 4 feet (120 cm) wide


  • 54 inches (135 cm) of 2 x 2-inch (5 x 5-cm) rough-sawn lumber
  • 44 feet (13-1/5 m) of 4 x 1-3⁄4-inch (10 x 4-cm) rough-sawn lumber in multiples of 4 feet (120 cm)—floorboards would make a good substitute
  • 13-1 ⁄4 feet (4 m) of 1-3⁄4 x 1-inch (4 x 2-3⁄4 cm) rough-sawn lumber
  • Eight 3-inch (8-cm) metal angle brackets
  • Three 2-inch (5-cm) hinges
  • Metal latch
  • Sixty 2-3⁄4-inch (6-cm) wood screws
  • Thirty-two 3⁄4-inch (2-cm) wood screws
  • 13-3⁄4-foot (360 cm) wooden batten Plastic sheeting 2-inch (5-cm) nails
  • Organic wood preservative


  • Drill
  • Screwdriver
  • Wood saw
  • Hammer
  • Paintbrush 


    1. The first job is to cut virtually all the wood into the following lengths:

    • two 12-inch (30-cm) lengths of 2 x 2 inches (5 x 5 cm)—front support posts
    • two 16-inch (40-cm) lengths of 2 x 2 inches (5 x 5 cm)—rear support posts
    • seven 4-foot (120-cm) lengths of 4 x 1-3/4 inches (10 x 4 cm)—front and back
    • eight 21-inch (52-1/2-cm) lengths of 4 x 1-3/4 inches (10 x 4 cm)—two sides
    • two 4-foot (120-cm) lengths of 1-3/4 x 1 inch (4 x 2-1/2 cm)—front and back of lid
    • three 21-inch (53-cm) lengths of 1-3/4 x 1 inch (4 x 2-1/2 cm)—end and central support of lid

    2. Cut down the lengths of two side pieces of wood so that 1 inch (2-1/2 cm) is removed from the length of each. The six lengths of wood that make up the main part of each side (three per side) are screwed to the supporting posts first, so that all wood is flush, ensuring that one of the cut-down pieces is on each side. Do not worry about the excess supporting post at the rear of the cold frame.

    3. Attach both the front and back lengths of wood so that they overlap the ends of the sides already in place. This will leave a box with gaps on the supporting posts on each side, but two spare 21-inch (52-1/2-cm) lengths of 4 x 1-3/4 inches (10 x 4 cm). Each of these can be held up to the gaps on the sides and the sloping cut from the back of the cold frame down to the front marked for sawing. Once sawn, screw in place. Using a saw, angle the tops of the rear posts so all the pieces of wood are flush. This forms the base of the cold frame, except for handles that will be used to move it.

    4. To make the handles, either cut hand-sized holes into each end if a jigsaw is handy, or attach small extra pieces from the 1-3/4 x 1-inch (4 x 2-1/2-cm) wood. The latter is done by screwing two vertical pieces into the sides; a horizontal piece of wood is then screwed in place to bridge the gap.

    5. To make the lid, attach the two 4-foot (120-cm) lengths of 1-3/4 x 1-inch (4 x 2-1/2-cm) wood and two of the 21-inch (53-cm) lengths of 1-3/4 x 1-inch (4 x 2-1/2-cm) wood together using four of the metal angle brackets. The lid needs to be exactly the same size as the top of the cold-frame base. Attach the last 21-inch (53-cm) length of 1-3/4 x 1-inch (4 x 2-1/2-cm) wood to the center of the lid using the remaining four brackets.

    6. Before going any further, treat the basic framework of the cold frame with an organic wood preservative.

    7. Now that the frame for the lid has been made, screw the hinges into place, with one hinge in the center of the back of the lid and the other two each 6 inches (15 cm) in from each end.

    8. To attach plastic sheeting to the top of the lid, place it over the lid with about 3 inches (8 cm) overhanging all around. Cut the wood piece into four pieces to correspond to the four sides of the box. Roll the plastic around each 1 x 2-inch (2-1/2 x 5-cm) wooden piece and nail onto the lid close to the outer edge, ensuring it is tight with no creases in it. I like to use plastic instead of glass or plexiglass because these two materials are easy to crack or break, particularly on windy days. Close the lid and screw the latch into place in the center of the lid and base.


• After you’ve made the lid of the cold frame, screw the hinges into place.

• Wood that measures 4 x 1-3/4 inches (10 x 4 cm) is commonly called “two-by-four.” The metric measurements are based on the actual, rather than the common, measurements.

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Reprinted with Permission from Organic Gardening Techniques and Published by Companion House Books.

Mother Earth Gardener
Mother Earth Gardener
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