How to Overwinter Plants in a Cold Frame

Greenhouses offer an amazing venue for overwintering plants, but purchasing and constructing one may be outside a gardener’s budget. Or it may be too large to fit on their property. Or perhaps it’s a bit too labor intensive.

A cold frame, however, is like a foot locker to a greenhouse’s locker room. Their functions are the same, but their sizes are drastically different.

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Low-tech cold frames have a small footprint, and they’re quite versatile. Any gardener looking to extend the growing season or offer protection for their plantings should consider adding one to their arsenal of garden tools.

In this guide to overwintering plants in a cold frame, you’ll learn everything you need to get started.

Here’s everything that’s in store, up ahead:

A cold frame operates similarly to a greenhouse – sunlight penetrates a transparent lid, which is absorbed by the flora and non-living material inside.

The sunlight is converted into heat energy that’s trapped within the structure, which raises its internal ambient temperature by about five to 10°F, on average.

It’s important to keep in mind that this will only allow you to achieve a minimal increase in temperature – this isn’t a structure that’s going to allow you to overwinter cucumbers in Alaska or anything like that.

While greenhouses are typically much larger in scale and often have supplemental heating systems, these structures are smaller and pretty spartan, relying only on the sun and maybe an external covering such as a mat or blanket for warmth.

In order to access, add, or remove plants, these mini-greenhouses should