Building a Coldframe

A cold frame can easily be made with salvaged materials and provide you with an earlier harvest come the new season.

A cold frame is like a mini greenhouse usually just a box with some sort of glass top to let the sun in. Our project uses some lumber, a couple of hinges and an old window!

What you will need:

  • (1) old window, measure all sides, if metal then you will need to add a
    wood frame made of either 2” x 2” or 1” x 2” wood, under the window so you can add the hinges needed in the back and legs to the sides so that you can prop window up for air circulation. If framing out, do this first before taking measurements to continue.
  • (1) 1” x 8 ”or (1) 2” x 8”, length equal to 1 long side of window, minus the thickness of wood used for the short sides x 2.
  • (2) 1”x 8” or (2) 2” x 8”, length equal to short side of window.
  • (1) 1” x 4” or 2” x 4”, length equal to 1 long side of window, minus thickness of wood used for short sides, same as in step 2.
  • (2) 2” x 2” pieces 3.5” in length and (2) 2” x 2” pieces 7.5” in length
  • (2) 1 x 2, 2 feet in length
  • (2) 1”x 2”, cut 6” in length each
  • (2-3) cabinet hinges
  • (1) heavy duty metal cabinet pull


  1. If framing metal window, do that first. Make the frame so the outside measurements are the same as the measurements of the window. Rest the window on top of the frame and secure to the frame using small angle brackets on each side overlapping the edge of the window.
  2. Cut the TWO shorter 1” X 8” OR 2” X 8” pieces lengthwise with the height of the 2” x 4” on one side going to the height of the 2” x 8” on the other end. This makes the window lay at a angle so water doesn’t collect on top of the window. Or SNOW!
  3. Lay out the bottom frame for orientation, the sides should overlap the front and back edges. Place short pieces of 2” x 2” on inside corners. These will be the corner brackets to hold the bottom together. Predrill 4 holes on each 2” x 2”, 2 on one side and 2 perpendicular to the others. Make sure they don’t run into each other.
  4. Using screws at least 2 ½” long, screw in corner, brackets to each side of the frame, thus attaching the sides to the back and front.
  5. Now, you should have the top window done and the bottom frame complete. Lay the window on top on the bottom frame. They should have the same outside dimensions. If not quite exact, that’s ok, as long as there isn’t any weight on the glass of the window. Position the window top so that it is flush with the back outside edge. Place cabinet hinges in place, making sure they will work in the direction intended.
  6. Attach hinges to window back side. Line up in position on bottom frame and attach.
  7. On the inside of both sides of the window frame, attach the TWO longer 1” x 2” pieces with 1 screw each so they can swing down to prop window up for air circulation.
  8. On the outside of the front of frame of window, attach TWO short 1” x 2” pieces with one screw each to frame so they can swing down to prop the window up a lesser amount for just a little circulation.
  9. Finally, add cabinet pull to front of window frame.
  10. Place in position with a sheet of landscape fabric on the bottom to hopefully keep the ground bugs out.
  11. When first using your cold frame, keep track of the inside temperature, due to the glass window, heat can build up and “cook” your seedlings if air circulation isn’t adequate!
  12. This cold frame is for the starting of seedlings in flats or small pots. One may also put soil directly into the cold frame to grow plants like salad greens until used.

<< Back