A cold frame helps protect your plants when harsh temperatures may harm them. Simply a box with a transparent cover, a cold frame collects heat to keep your plants warm and shields them from the elements throughout the winter or summer seasons.
During warmer months, a cold frame provides an ideal environment to move seedlings outdoors or to grow a crop of fresh greens.
Making this simple box is an easy, handy project that will keep your plants warm and happy all year long.
cut list for the wood:
- Four 2 x 6 x 27-inch boards
- Four 2 x 6 x 36-inch boards
- Four 4 x 4 x 11-inch boards
- Four 1 x 3 x 36-inch boards
- Four 1 x 3 x 25 ½-inch boards
Remember: Measure twice, cut once.
Tools and Materials:
- Two 2 x 6 x 12-foot redwood boards
- Two 1 x 3 x 12-foot redwood boards
- Measuring tape
- Chop saw
- 7/64-inch drill bit
- 2 ½-inch stainless steel deck screws for the box
- 1 1/4-inch stainless steel screws for the lid
- 36 x 30 x .093-inch acrylic sheet
- Marking material, string or chalk dust
- Three hinges
- Potting mix
STEP 1 – Build two sides.
- Lay two 4 x 4-inch pieces 19 inches apart.
- Lay two 2 x 6 x 27-inch pieces on top of the 4 x 4 pieces so that the ends of the 2 x 6 pieces are flush with the sides of the 4 x 4 pieces.
- Drill two 7/64-inch pilot holes and secure with 2 ½-inch deck screws on each end of the 2 x 6-inch pieces into the 4 x 4-inch pieces to create a side.
- Repeat step one to make another side of the frame.
STEP 2 – Build the other two sides.
- Space the two sides you built 36 inches apart.
- Stack two pieces of 2 x 6 x 36-inch boards upright against the two sides creating the third side of the box. Corners should be at a 90 degree-angle.
- Drill pilot holes and secure with two screws through the 2 x 6-inch pieces into the 4 x 4-inch pieces.
- Repeat step two to complete the fourth side of the box and creating a rectangle.
STEP 3 – Build the top.
- With this step you will be creating a double framed window.
- Using the 30 x 36-inch acrylic sheet, place 1 x 3 x 36-inch pieces on the top and underside of the 36-inch length ends of the acrylic, creating the top and bottom. All edges should be flush with one another.
- Clamp to hold in place.
- Place a 1 x 3 x 25 ½-inch piece on the top and underside of the shorter sides of the acrylic sheet. You should have a 90-degree rectangle frame on the top and bottom of the acrylic, like a sandwich.
- Clamp to hold in place.
- Drill four evenly spaced pilot holes through the 36-inch underside wood pieces and acrylic and into the top pieces of wood.
- Drill three evenly spaced pilot holes through the underside 25 ½-inch pieces of wood and acrylic and into the top piece of wood. Do not go through the top piece of wood.
- Secure with 1 1/4-inch stainless steel deck screws.
STEP 4 – Prepare the area and place the frame.
- Place your cold frame in a location where it will get at least six hours of sun per day and outline the area.
- Remove the frame and dig six inches deep to keep the soil warmer during cold months.
- Set the frame back in the hole.
- Use three hinges to attach the top to the frame.
- Mark the holes of the hinges and drill pilot holes for the screws.
- Secure the hinges with the supplied screws.
- Attach a handle for easy lifting.
- Mix in potting soil and plant your favorite vegetables. You can also put flats of plants directly onto the soil.