8 Cold Frame Plans for Year-Round Gardening

Expand your growing season and upcycle local materials by building one (or a few!) of these inexpensive DIY cold frames.

| August/September 2016

A humble cold frame offers a great way to produce nutritious, homegrown food outside of the prime growing season without investing in a full-sized greenhouse. Although many gardeners already use these mini-greenhouses to shelter seedlings before planting in spring, they may not realize that crops will stay alive inside a cold frame during winter, providing fresh food from the garden in December, January, and even February.

Commercial cold frames can make beautiful additions to your garden, but an inexpensive DIY setup is a great way to get started. You can quickly assemble one or more DIY cold frames with upcycled materials, and then move them around your property to find the best microclimate before you install a more elegant cold frame.

Jump in with any of these eight cold frame plans, chosen for simplicity and low cost.

Using a Cold Frame

At its simplest, a cold frame is a box supporting a transparent top that admits sunlight. The top typically lifts to provide access to the crops living inside. The bottom is usually open to garden soil, allowing crops’ roots to dig deep. Using a cold frame is the equivalent of moving your garden one growing zone to the south. Adding a cold frame to the interior of an unheated greenhouse is the equivalent of moving your crops two zones south.

You should begin by identifying the best places on your property for growing cold-hardy crops. You’ll want to establish a cold frame in direct sunlight, atop good soil in a well-drained location that has easy access to the house — a long walk from the kitchen to the cold frame can be unpleasant in January! Ideally, you should maximize the cold frame’s effectiveness by angling its transparent top to the south, where the sun hangs low in winter.

Gardeners in cold regions — Zone 6 or less — can boost temperatures inside their frames by adding thermal mass to the interiors, or by insulating their cold frames’ sides with mounded-up soil, straw bales, or bags of leaf mulch. Growers in low-light regions can paint their cold frames’ interior white or add metal foil to reflect minimal sunlight. To prevent excess heat from wilting your plants, always vent your cold frame on sunny days when the temperature will rise above 50 degrees Fahrenheit. Just crack open the lid during the day and close it again at twilight.

8/22/2016 5:54:09 PM

burtbear, I had an old fiberglass shell I had laid on the ground. Well, almost on the ground... it had a couple of 2x4's to keep it just up and off the grass. Anyhow, when we'd get some snow (and because it was slightly raised, it would blow under there and pile up a bit. I can tell you for about 4" around the side, and rear glass, the snow would melt when the sun came out. Snow that wasn't touched by the sun took many days longer to do so. Not scientific by any means, just and observation as I too had the idea to try that.

8/17/2016 5:03:02 PM

I wonder if I can use my old pickup bed top as a cold frame? It has windows on all four sides and three that can be opened and closed to control the heat. Old dented or out of style tops are numerous. What are the drawbacks to using old truck tops as cold frames?

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