Did you know you can build a cold frame out of pallets for next to nothing?

It’s true! If you have a few old windows and an assortment of random hinges on hand, plus access to free pallets, these cold frames will cost you nothing. Don’t have these supplies on hand?  No worries, they’re not hard to track down.  

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Keep your eyes open for random free pallets (always ask before carting them off) or ask at your favorite nursery, farm supply store, or wherever you notice lots of pallets stacked in the parking lot.

Depending on where you live, you might need to get creative when searching for old windows.  If you live near the east coast where buildings are older, vintage windows are easier to come by.  My dad has an old barn and he’s also in construction, which means there’s often cool stuff just hanging out in his barn.  I’ve also driven past places that sell old windows and doors, and I’ve seen them for sale at Habitat for Humanity Restores.

Still stumped?  Consider checking with your local glass and window replacement shop.  You may be able to intercept old windows headed for the landfill.

We bought our pallets for $2 each at a local farm supply store.  And Mr. Native Texan was thrilled to find a use for that large stash of (really cool) old windows I’ve been saving. I wouldn’t let him get rid of said windows because they were free to us and I was so sure we’d find a good use for them someday… See?  It all worked out.

Cold frames can help to extend the gardening season, allowing you to plant earlier in the spring and keep the harvest going longer in the fall.  Some varieties can even grow through the winter when protected inside a cold frame!

We plan to use our cold frames mainly for winter salad green annuals such as spinach, mâche and claytonia, based on the excellent suggestions in The Winter Harvest Handbook by Eliot Coleman.

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Winter is the perfect time to build cold frames out of pallets.  In the absence of intensive garden tasks, most gardeners tend to have more spare time around January and February.  Of course you can build a cold frame any time of the year, and mid to late fall is when you’ll really want to start using your cold frame.

We chose to build a cold frame out of pallets and other simple supplies we already had on hand.  This keeps the cost low and the size manageable. Read on for step by step instructions with lots of pictures…

How to Build a Cold Frame Out of Pallets

Supplies:

• 1 old window
• 2 pallets with similarly sized slats
• Two flat hinges
• 1 1/2″ screws (wood, drywall, etc., whatever you have on hand)

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Tools:

• Circular saw
• Miter saw (optional)
• Drill
• Small drill bit (to drill pilot holes)
• Screw driver
• Hammer
• Pliers (optional)

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Step 1: Dismantle Pallets

1. Use the circular saw to cut the edges of the pallet away from the rest of the pallet.
2. Gently bend the slats to separate from the center board. (You may need to tap the slats lightly with a hammer.)
3. Use the hammer to remove any remaining nails from the slats.  (Tap lightly on the pointed end of the nails until the nail head sticks out far enough to be grabbed with the claw end of the hammer or with pliers. ) Kids can help, too!

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Step 2: Assemble Back & Front Walls

1. Measure the width of the window, then subtract the pallet slat thickness times two.  This will be the width of your front and back walls. (Example: For a 28″ wide window and 3/4″ thick pallet slats, you’d double 3/4″ to get 1.5″.  Subtract 1.5″ from 28″ to get 26.5″.)
2. For the back wall: cut three to four slats to construct a back wall roughly 1.5 ft high.  Use the measurement from step #1 for the width.
3. For the front wall: repeat steps 1 & 2, using one less slat.
4. Every pallet has three 2×4  support boards.  Use these to cut four sections–two to match the height of the back wall and two to match the height of the front wall.  You will attach the front and back walls to these sections.
   

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5. Form the back wall by attaching the back slats to the taller set of supports.  To avoid splitting the wood, you may want to drill pilot holes first.
6. Form the front wall by attaching the front slats to the shorter set of supports.  To avoid splitting the wood, you may want to drill pilot holes first.

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Step 3: (Partially) Assemble Side Walls

1. Measure the length of the window.
2. Cut enough slats at that length to complete the two side walls up to the approximate height of the front wall.  (Try to save the widest slats for the angled top pieces, to be cut later.)
3. Attach the side slats to the front and back walls with screws.  Drill pilot holes first, if necessary.  Start at the bottom of each side and work your way up. Stop when the side walls are just shy of the front wall height. You will fill in that last angled piece later…

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Step 4: Attach the Window

1. Use two hinges and screws to attach the window to the back wall.
2. Position each hinge a few inches from the edge of the window frame.

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Step 5: Finish the Side Walls

1. Cut the final two slats to fit the triangular opening on each side wall.  For the first box, we held the slat up to the opening and used a pencil to trace the angled line, keeping the bottom of the slat even with the top of the side wall.  For subsequent boxes, we measured the sides and bottom of the opening and used those measurements to determine the angled line.
2. Screw the angled boards to the back of the cold frame.
3. To secure the front of the angled board:
   1. Find the middle point of each side wall and measure the height from top to bottom.
   2. Use this measurement to cut two extra pallet slats to serve as supports for the side walls.  (The slat width doesn’t matter.)  These support slats won’t be highly visible, so it’s fine to use scrap pieces of pallet.  
   3. Attach the side supports to the middle point of each side wall, on the inside of the box.  This will hold the angled piece firmly in place.

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You should now have a functional cold frame.  Hooray!

Venting the Cold Frame

We’re using a super simple method to vent our cold frames: one extra pallet slat per cold frame.

• To vent the box just a little, we place the slat across the front of the box, resting the window on top.
• To vent the box a little more, we slide the wooden slat to the rear / back of the box.
• To vent the box all the way, we open the window completely and lean it back against the fence.

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We’re super pumped to experiment with our new cold frames this year!
Have you ever used a cold frame or built one yourself?

All about seed-starting:

• 12 Best Veggies for Your Spring Garden
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• DIY Straw Bale Cold Frame
• How to Harden Off Seedlings

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Lets Grow! Garden Planning Course

Plan your best garden with simple, step-by-step instructions!

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