![The window frame top of a cold frame opens slightly to show the plants inside. The window frame top of a cold frame opens slightly to show the plants inside.](https://contentgrid.homedepot-static.com/hdus/en_US/DTCCOMNEW/Articles/how-to-build-a-cold-frame-2022-hero.jpg)
Difficulty
Intermediate
Duration
2-4 hours
You can extend the growing season in your garden with a cold frame. Think of a cold frame as a simple greenhouse that sits close to the ground. To allow light in, the top of the cold frame may be made of glass, fiberglass or plastic. The cold frame helps to hold the sun’s warmth overnight, shielding plants from frost and freezing temperatures.
This guide will show you how to build a cold frame with wood and plastic sheeting.
- Gather Tools & Materials
- Cut the Wood
- Make the Base of the Cold Frame
- Cut the Wedges
- Attach the Wedges
- Lay Out and Measure the Top of the Cold Frame
- Cut the Joints
- Chisel the Wood
- Glue the Pieces of the Top in Place
- Attach the Window Panels
- Place the Top of the Cold Frame on the Base
- Add a Handle
- Choose a Place for the Cold Frame
- Tips for Using a Cold Frame
Gather Tools & Materials
![A worktable displays the tools and materials needed to make a cold frame, including a hammer, a level, a drill and a circular saw. A worktable displays the tools and materials needed to make a cold frame, including a hammer, a level, a drill and a circular saw.](https://contentgrid.homedepot-static.com/hdus/en_US/DTCCOMNEW/Articles/how-to-build-a-cold-frame-2022-step-1.jpg)
A DIY cold frame can be constructed in several different ways. Some cold frames are made with upcycled window frames. Others look like tiny tents and sit on top of your plants.
For this project, you will use wood and sheets of plastic to build a cold frame.
Materials list:
Two 2- x 6-inch x 8-foot cedar boards
Two 1- x 4-inch x10-foot cedar boards
3-inch exterior screws
3/4-inch exterior screws (may be provided with hinges and handle)
Exterior wood glue
24 mirror clips
Six 8- x10-inch pieces of clear plastic
2 Hinges
1 Handle
Tools:
Pencil
Tape measure
Straight Edge
Speed square
Circular saw
Table saw (optional)
Drill with 1/8-inch bit for pilot holes and driver bit for screws
Sharp chisel
Hammer or mallet for chiseling
Cut the Wood
![A person cuts a board with a circular saw. A person cuts a board with a circular saw.](https://contentgrid.homedepot-static.com/hdus/en_US/DTCCOMNEW/Articles/how-to-build-a-cold-frame-2022-step-2.jpg)
Cut List for the Cold Frame
- Begin by measuring and cutting the two 2- x 6-inch x 8-foot cedar boards to three pieces at 24 inches and three pieces at 33 inches. These will be the sides of the cold frame.
- Cut the two 1- x 4-inch x10-foot cedar boards to three pieces at 36 inches each and four pieces at 24 inches.
Make the Base of the Cold Frame
![A man drills a hole in one of the boards that forms the outside of a cold frame. A man drills a hole in one of the boards that forms the outside of a cold frame.](https://contentgrid.homedepot-static.com/hdus/en_US/DTCCOMNEW/Articles/how-to-build-a-cold-frame-2022-step-3.jpg)
This cold frame will be 36 inches in the front and back and 24 inches on each side.
- To make the base of the cold frame, lay the two 36-inch pieces of wood parallel to each other, about two feet apart. They will serve as the front and back of the cold frame.
- Place the 24-inch pieces of wood on either side of the two 36-inch pieces to make a rectangle.
- Use 3-inch screws to connect the side pieces to the front and back pieces.
Cut the Wedges
![A man uses a straight edge and a pencil to draw a cut line on a board for a wedge of a cold frame. A man uses a straight edge and a pencil to draw a cut line on a board for a wedge of a cold frame.](https://contentgrid.homedepot-static.com/hdus/en_US/DTCCOMNEW/Articles/how-to-build-a-cold-frame-2022-step-4.jpg)
You'll need to cut wedges to sit on top of the base of the cold frame. These wedges will make the cover of the cold frame sloped. This downward slope will let rain run off the cold frame.
Diagonally cut one of the 24-inch long pieces of 2- x 6-inch cedar. This will make two wedges, one for each side of the cold frame.
Attach the Wedges
![A person drills a hole in the wedge of a cold frame. A person drills a hole in the wedge of a cold frame.](https://contentgrid.homedepot-static.com/hdus/en_US/DTCCOMNEW/Articles/how-to-build-a-cold-frame-2022-step-5.jpg)
Screw the wedges to the sides of the cold frame base using 3-inch screws.
Lay Out and Measure the Top of the Cold Frame
![A person uses a measuring tape to measure the distance between the panes of the top of a cold frame. A person uses a measuring tape to measure the distance between the panes of the top of a cold frame.](https://contentgrid.homedepot-static.com/hdus/en_US/DTCCOMNEW/Articles/how-to-build-a-cold-frame-2022-step-8.jpg)
- Lay out the four of the 24-inch 1- x 4-inch wood pieces for the window frame top.
- They should be placed in a window-pane configuration. The 36-inch boards should be placed horizontally and the 24-inch boards should cross them vertically.
- The space between the wood pieces of each pane of the top of the cold frame should be just smaller than the 8- x 10-inch clear plastic pieces.
- Use a square to make sure the wood pieces are properly placed.
- Use a pencil to mark the locations for the half lap joints.
Cut the Joints
![A person uses a circular saw to cut pieces of wood for the top of a cold frame. A person uses a circular saw to cut pieces of wood for the top of a cold frame.](https://contentgrid.homedepot-static.com/hdus/en_US/DTCCOMNEW/Articles/how-to-build-a-cold-frame-2022-step-6.jpg)
Cut the joints by setting your saw’s cut depth to half of the material’s thickness. For example, half of 3/4-inch is 3/8-inch.
Chisel the Wood
![A person uses a hammer and a chisel to chip wood off a board that will be used to make the top of a cold frame. A person uses a hammer and a chisel to chip wood off a board that will be used to make the top of a cold frame.](https://contentgrid.homedepot-static.com/hdus/en_US/DTCCOMNEW/Articles/how-to-build-a-cold-frame-2022-step-7.jpg)
Make multiple cuts to weaken the wood. Then use a chisel to clean out the waste.
Glue the Pieces of the Top in Place
![A person holds down a small piece of wood that is being glued to a larger piece on the top part of a cold frame. A person holds down a small piece of wood that is being glued to a larger piece on the top part of a cold frame.](https://contentgrid.homedepot-static.com/hdus/en_US/DTCCOMNEW/Articles/how-to-build-a-cold-frame-2022-step-9.jpg)
Once you have the parts of the top of the cold frame cut and in place, glue the 36-inch wood pieces to the 24-inch pieces to make the panes. Gluing the wood will make a nice flush cover for the cold frame. Clamp each joint as you glue.
Attach the Window Panels
![A person uses a drill to attach screws to the corner of a cold frame. A person uses a drill to attach screws to the corner of a cold frame.](https://contentgrid.homedepot-static.com/hdus/en_US/DTCCOMNEW/Articles/how-to-build-a-cold-frame-2022-step-10.jpg)
- Drill a hole in the corners and in the center of the sides of each of the 8- x 10-inch plastic panels. You will drill a total of eight holes in each one of the panels.
- Place screws in the holes of each panel. Attach the screws to the underside of the window-pane top of the cold frame.
- You can use fiberglass or glass panels instead of plastic sheeting. However, if kids or pets play will be playing near the cold frame, don't use glass. It can be easily broken.
Place the Top of the Cold Frame on the Base
![A person uses a drill to drive screws into the hinges that attach the top of cold frame to the base. A person uses a drill to drive screws into the hinges that attach the top of cold frame to the base.](https://contentgrid.homedepot-static.com/hdus/en_US/DTCCOMNEW/Articles/how-to-build-a-cold-frame-2022-step-11.jpg)
- Attach the hinges to the window top of the cold frame first. Place the top on the cold frame and check to make sure it is lined up corrected.
- Then screw the hinges to the cold frame base.
- The finished cold frame will measure 36 inches at the back and 24 inches on each side.
Add a Handle
![A person uses a drill to drive screws to attach a handle to the top of a cold frame. A person uses a drill to drive screws to attach a handle to the top of a cold frame.](https://contentgrid.homedepot-static.com/hdus/en_US/DTCCOMNEW/Articles/how-to-build-a-cold-frame-2022-step-12.jpg)
When you’re done building a cold frame, you can add a handle to it to make it easier to open and close. Attach the handle to the lid close to the bottom edge, in the center. Use 3/4 screws to fasten the handle to the cold frame.
Choose a Place for the Cold Frame
![A person kneels next an open cold frame to take out one of the cabbages growing inside it. A person kneels next an open cold frame to take out one of the cabbages growing inside it.](https://contentgrid.homedepot-static.com/hdus/en_US/DTCCOMNEW/Articles/how-to-build-a-cold-frame-2022-step-13.jpg)
After putting a handle on your DIY cold frame, choose a place to put it. The ideal spot will receive sun all day and will usually be in the south-facing side of your yard.
Tips for Using a Cold Frame
![A man kneels in front of cold frame, holding it open with one hand and holding a small head of cabbage in the other hand. A man kneels in front of cold frame, holding it open with one hand and holding a small head of cabbage in the other hand.](https://contentgrid.homedepot-static.com/hdus/en_US/DTCCOMNEW/Articles/how-to-build-a-cold-frame-2022-step-14.jpg)
- Raise the lid on your cold frame when the temperature hits 40 degrees F or above, so the heat doesn’t build up and cook your plants.
- Close it in the afternoon to trap warmth overnight.
- Use a stick to prop the lid open for ventilation on warm, sunny days. Cut notches in the stick so you can control how high to raise the lid. If needed, use a shade cloth to lower the temperature of the cold frame.
- Don’t use glass for your cold frame if your area gets snow or ice. The built-up of snow or ice could break the glass. If you have children or pets, avoid using glass to build your cold frame, as well.
- Automatic vents aren’t recommended where snow and ice may keep the vent from operating.
- Angle the cold frame so that the back is higher than the front. This setup helps capture more light and lets rain run off the roof.
- For extra protection, place the cold frame next to a building.
- For additional insulation, dig 6- to 8-inches into the soil and build your cold frame partly below ground. If you’re concerned about flooding, add a layer of gravel underneath.
- When the temperatures drop to 20 degrees F or below, protect the cold frame by layering old blankets on top. You could also use electrical heating cables to warm your cold frame.
When you know how to build a cold frame, you can expand the growing season for fresh produce in your yard. During the colder months, spinach, lettuce and other greens can thrive in a DIY cold frame. Other vegetable that are well suited for a cold frame include carrots, radishes and leeks. In the spring, a cold frame can serve as a place to start seedlings.
Ready to get the tools and materials to build a cold frame? The Home Depot delivers online orders when and where you need them.