Build a DIY cold frame using an old window

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One of the projects that I knew I wanted to include in my book, Raised Bed Revolution, was a cold frame. I had seen some neat DIY cold frame examples through garden visits over the years, great cold frame kits through various retailers and innovative cold frames that used old windows as the lid. I was also inspired by Niki, who gardens 365 days a year (you can find some of her cold frame tips here).

When the photographer for my book, Donna Griffith, grabbed an old window a mutual friend was giving away, I enlisted my brother-in-law, Deon, to help me figure out how to build a cold frame to fit.

You could also use clear plastic for the lid. The idea is that the glass or plastic will harness the winter sun’s warmth, allowing plants to grow inside. Now we’re not talking tomatoes here, but there are several things you can grow, including root vegetables and greens. One thing I read about cold frame designs is that the back should be about three to six inches higher than the front, which helps capture as much solar energy as possible.

Here are the steps for my DIY cold frame

You can adjust measurements based on the size of the lid you want to use.

DIY cold frame project plan

Illustrated cold frame project plan


  • Miter saw
  • Circular saw or jigsaw
  • Japanese dozuki saw
  • Orbital sander or sandpaper
  • Power drill or impact driver
  • Straight edge and pencil
  • Clamps (optional)
  • Tape measure
  • Eye and ear protection
  • Work gloves

Note: This project was made to accommodate an old window that’s 32 1⁄4″ long × 30″ wide.

  • (4) 1 1/2″ × 6″ × 8′ cedar boards
  • (2) hinges
  • 2 3⁄4″ screws

Cut list

  • (5) front and back pieces measuring 1 1/2 × 6 × 32 1⁄4″
  • (4) side pieces measuring 1 1/2 × 6 × 30″
  • (2) angled side pieces (see instructions) measuring 1 1⁄2 × 5 1⁄2 × 30″
  • (2) corner braces (cut from scrap) measuring 1 1⁄2 × 6 × 16 1⁄2″
  • (2) corner braces (cut from scrap) measuring 1 1⁄2 × 6 × 11″

Step 1: Build the frame

Lay out the 32 1⁄4-inch front and back pieces so that they cover the sides of the 30-inch side pieces to form a box. Screw in place to make the bottom of the frame. Repeat this step to create the second layer. For the third layer, there is a back piece but no front piece because of the angled slope you want to create once the window is attached. This means the side pieces need to be cut at an angle. They also need to be longer to accommodate the slope. Leave about 10 inches on the end in order to either screw or clamp the work piece down to your bench for when you make the cut. Screw the side piece to the back piece temporarily, and place on top of the box. Take a straight edge and place it from the edge of the top corner to the front of the box diagonally across the board and draw a line. Remove the temporary screws and attach the extra 10-inch length to your work table with clamps or screws. Use a circular saw or jigsaw to slowly cut it out as you’re going across the grain. One cut gives you both angled side pieces. Trim the extra 10 inches off the one piece to length.

DIY cold frame: Step 2

DIY cold frame: Step 2

Step 2: Sand the side pieces

Use an orbital sander or sandpaper to smooth the rough edges of the angled side pieces.

DIY cold frame: Step 3

DIY cold frame: Step 3

Step 3: Attach the angled side pieces

Place the two angled side pieces inside the edges of the third back piece and fasten in place from the back. There is no front piece for the third level of this assembly because of the angle of the final project. Add an extra screw on each side toward the front to secure the side pieces in place because they will not attach to the corner braces.

DIY cold frame: Step 4

DIY cold frame: Step 4

Step 4: Install the corner braces

From one of the remaining cedar boards, cut two pieces that are 2 × 16 1⁄2 inches and two pieces that are 2 × 11 inches. The long pieces are the braces for the back corners. Cut the ends of these on a slight angle to accommodate the gentle slope of the tops of the angled side pieces, or you can cut a bit shorter and install them below the angle. The window should close without leaving a gap further down. From the inside, screw these four braces to the outside frame to secure it in place.

Step 5: Trim the front

If there is a bit of wood from the two angled pieces overlapping the front, use a dozuki handsaw or the orbital sander to gently trim it away.

DIY cold frame: Step 6

DIY cold frame: Step 6

Step 6: Attach the hinges

The preexisting metal piece along the back of the old window would have prevented the screws for the hinges from going in, so two scrap pieces of wood were trimmed and used to create a new “back” to which the hinges could be attached. This also pushed the window forward a bit to make up for the extra centimeters that were added from the diagonal. Once these scraps are screwed in place, attach the two hinges to the window frame and the frame of the box.

Once you start using your cold frame, it’s important to know that things can get a little too heated inside, so it’s important to vent the cold frame sometimes, even in the winter. I just use an old piece of wood to prop mine open, but you can also get automatic vent openers that will gauge the temperature and open accordingly.

finished DIY cold frame

The cold frame is ready for cold-season crops, such as beets, carrots, greens, etc.

Project designed by Deon Haupt and Tara Nolan
All photography by Donna Griffith
Technical illustration by Len Churchill

Excerpted with permission from Cool Springs Press

For more on cold frame gardening, check out these posts: 

DIY Cold Frame Plans with Step-by-Step Instructions

Related Posts

12 Responses to Build a DIY cold frame using an old window

  1. Brad says:

    Wow, this looks like a great idea. Which is better: A cold frame or the mini hoop house? Or have both? Are certain vegetables better for these?


    • Tara Nolan says:

      They both have their benefits when it comes to planting cool-weather veggies and extending the growing season (or getting a head start!). Depending on what materials you use for the mini hoop house and how harsh the winter is, the structure may not withstand the weather, in which case a cold frame would protect your crops from the elements.

  2. Michele says:

    HI Tara great presentation last night in Glen Morris, I am
    Going to put my husband to work making me a cold frame

    Thank you

  3. snibb says:

    The instruction for how to attach hinges to a metal frame aren’t very poor. How big are the scrap pieces of wood? This should be mentioned when considering how to measure for other parts of the cold frame because it affects how much the glass overhangs the front of the box. And, how do you attach the wood to the metal without breaking the glass?

  4. Amy from VA says:

    Dumb question from a newbie: what do you do with the cold frame after warm weather comes… do you remove the window and just use the bed or remove the plants into a raised garden? Thank you. I have two old window ready to go.

    • Tara Nolan says:

      There are no dumb questions, Amy! You can remove the window so that the raised bed space doesn’t go to waste, and then reattach in the fall when you’re ready for it to become a cold frame again. 🙂

  5. Mary Ginter says:

    How do you view the short clip videos? I saw something on the winter harvest seedlings W a plastic gallon jugs and then a video on the three different sizes W netting covers for a patio garden , can’t remember the name of it to be able to order some. Black bottoms W domed netting canopies if that helps you. Lol

  6. Kat Greene says:

    Hi—I am planning to make a couple of these, but have a question. How do you get 2 1/2 inch x 16 1/2 inch pieces from lumber that is only 1 1/2 inch thick (for the braces)?

    • Tara Nolan says:

      Hi Kat, I couldn’t totally remember, but I went out to measure and the braces are 1 1/2 x 2. I’ve amended the directions accordingly. Please let me know if you have any further questions!

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