Colorado’s growing season can be short, but a cold frame helps extend it and protect young plants. Using recycled materials makes the project both budget-friendly and eco-conscious.
I love turning old windows, scrap wood, or leftover boards into a cozy little shelter for seedlings. With a simple setup, your plants can thrive even when the Colorado nights get chilly.
Building a cold frame is a practical, creative way to give your garden a head start and make the most of every season.
1. Old Window Wonders
Got an old window replacement project? Don’t toss those frames! Hinged atop a simple wooden box, they create perfect cold frames with built-in glass tops.
Colorado’s intense sunshine will warm your seedlings beautifully through these repurposed windows. Just remember to prop them open on warmer days to prevent overheating.
2. Straw Bale Simplicity
Arrange straw bales in a rectangle, then lay an old shower door or window across the top. The straw provides excellent insulation against Colorado’s freezing temperatures while slowly decomposing.
No carpentry skills needed for this method! By spring, those bales will begin breaking down, creating rich compost for your garden beds.
3. Plastic Bottle Brilliance
Collect clear 2-liter soda bottles and cut off the bottoms. Push them into soil around individual plants as mini greenhouses or connect multiple bottles for larger protection.
Many Colorado gardeners have found this works surprisingly well for small seedlings. The plastic creates a greenhouse effect while the open bottle top allows for temperature regulation.
4. Pallet Frame Foundation
Free wooden pallets are everywhere in Colorado’s commercial areas. Stand four pallets on edge to form a square, secure the corners, and cover with salvaged plastic sheeting or an old window.
The gaps between pallet slats actually help with airflow while still providing structure. Add some old blankets on extra cold Front Range nights for additional insulation.
5. Cinder Block Boundaries
Leftover cinder blocks from construction projects make perfect cold frame walls. Arrange them in a rectangle, placing them hollow-side down to create insulating air pockets.
Colorado gardeners appreciate how these blocks absorb daytime heat and release it slowly overnight. Top with old windows or clear plastic stapled to a wooden frame for an instant growing space.
6. Salvaged Door Delight
Found an old glass door at a Colorado reuse center? Prop it at an angle against a south-facing wall, creating a triangular growing space beneath. Seal the sides with scrap wood.
The slanted design captures maximum sunlight during our bright Colorado days. Add some dark-colored rocks inside to absorb heat and release it slowly overnight.
7. Hay Bale Housing
Similar to straw bales but denser, hay bales create super-insulated walls for cold frames. Arrange in a rectangle and cover with an old window or plastic sheeting supported by scrap lumber.
Colorado’s dry climate helps these bales last through the season without excessive decomposition. Place in a spot that gets maximum winter sun exposure for best results in our mountain state.
8. Bubble Wrap Barrier
Large bubble wrap sheets from packages can create excellent insulation layers. Attach to the inside of any cold frame structure to trap additional heat while still allowing light through.
Colorado gardeners dealing with high-altitude temperature swings find this extra layer crucial. The air bubbles provide insulation while the clear plastic allows precious sunlight to reach your plants.
9. CD Case Creativity
Remember those plastic CD cases gathering dust? Tape them together to create a mini greenhouse top for your cold frame. The clear plastic allows light while trapping heat.
This upcycling project works wonderfully in Colorado’s sunny climate. The cases can be arranged in different patterns to fit whatever base structure you’ve built from other recycled materials.
10. Milk Jug Miniatures
Gallon milk jugs with bottoms removed become perfect mini cold frames for individual plants. Simply place over seedlings and push slightly into soil to anchor.
Colorado’s intense UV light makes these jugs break down eventually, so they’re perfect for temporary spring protection. When surprise May snowstorms hit the Front Range, you’ll be glad to have these ready!
11. Plastic Sheeting Shelter
Salvaged clear plastic sheeting from construction sites or packaging can transform any frame into a cold frame. Stretch over hoops made from old irrigation tubing or flexible branches.
Many Colorado gardeners use this method for quick protection during our unpredictable spring weather. The plastic traps solar heat during our abundant sunny days while protecting tender plants from overnight freezes.
12. Brick Border Base
Leftover bricks from landscape projects make excellent cold frame walls. The thermal mass absorbs daytime heat and releases it slowly overnight, creating a stable environment.
Stack them without mortar so you can reconfigure as needed throughout Colorado’s changing seasons. Top with an old window, shower door, or plastic sheeting for an instant growing space that’s both sturdy and efficient.
13. Wine Bottle Warmth
Fill dark glass wine bottles with water and place inside any cold frame along the north wall. During Colorado’s sunny days, these bottles absorb heat and release it overnight.
This passive solar technique is perfect for our state’s dramatic temperature swings. The water-filled bottles act as thermal mass, moderating temperatures and protecting your plants from freezing even at higher elevations.
14. Reclaimed Cabinet Conversion
Found an old cabinet at a Colorado ReStore? Remove the back, lay it on its side, and replace the top with clear plastic or glass. Instant cold frame!
The solid sides provide excellent protection from our strong mountain winds. Cabinet drawers can be removed or left in place to create different growing zones with varying heights for different plants.
15. Snow Fence Framework
Old wooden snow fencing, common throughout Colorado, makes perfect cold frame sides. Cut to size, form a rectangle, and cover with clear plastic or an old window.
The slats allow some air circulation while still providing structure and wind protection. Many high-altitude Colorado gardeners find this balance of airflow and protection perfect for hardening off seedlings before planting.