How to Build a Straw Bale Cold Frame

Straw bales are a great way to build easy, functional, and inexpensive cold frames. Here’s how to build a simple straw bale cold frame…

Cold frames can be a great way to extend your garden season later into the winter, or get your plants started earlier in the spring. Cold frames don’t need to be elaborate or expensive. In fact, many people put them together out of scrap wood and old windows – or, in this version, straw bales!

You can often find straw bales for free at the end of the fall season at garden centers or department stores when they take down their outdoor fall displays. They are simple to work with, and in fact, a straw bale cold frame has advantages that other cold frames don’t because of the superior insulation they provide. Straw bale cold frames are not only easy to build, but will keep your tender plants toasty warm when it’s cold outside!

You may be able to get a couple of seasons of use out of your straw bale cold frame, and when the straw starts to break down, simply add it to your compost pile – or use it as animal bedding – and set up a new one with fresh bales.*

Below are instructions for creating a simple straw bale cold frame.

* (Note: Some straw bales are not suitable for the compost as they may contain herbicide residues that could harm your garden plants. If you are not sure of the source of your bales, you may want to avoid using them in the garden. However, you can still use them as a cold frame as long as you are not planting into the soil inside, but simply putting potted plants, flats, or other containers in the cold frame.)

You Will Need

Straw bales

Old windows**

8 pieces of ½-inch by 24-inch rebar (optional)

2 8-inch wood stakes

A ‘mini’ sledgehammer

**The total window area should be roughly 4 to 6 feet by 4 to 6 feet – the exact dimensions aren’t that important because the structure can be adjusted to match. The number of bales needed depends on the size of the windows, as well as the size of the bales.

Step One – Arrange the Bales

Determine which direction is south (hint: it’s at the midpoint between where the sun rises and where it sets) and arrange two bales lengthwise facing that direction. Then place a bale on either end in a perpendicular position to form a three-sided structure. These two bales should be placed so they rest on their skinny side, making them taller than the first two.

Step Two – Place the Windows

Lean the windows against the shorter bales at the back of the three-sided structure, allowing the other edge to rest on the ground in front (this creates a slanted surface that is angled toward the sun as it passes through the southern half of the sky). Now, adjust the two side bales to close off the space between the windows and the ground. Drive a wooden stake in the ground at the base of each window so they don’t slip off the straw bales at the other end. Larger windows may require an additional bale on each side to close off the space between the windows and the ground.

Step Three – Secure the Bales (Optional)

This is optional, but a good idea if you want the most airtight and secure cold frame. If you are only using the cold frame for a couple of months, you can skip this step…

See full instructions, diagrams, & cold frame use tips at


Rose S.

An avid gardener since childhood, I love sharing my passion for gardening with others! I have gardened in a number of different climates and settings, from large fenced garden plots, to tiny patio and container gardens, and I firmly believe that everyone can learn to grow at least some of their own food - no matter where you live. Growing your own food can help you take control of your own health and food supply, and there has never been a better time to get started!

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