DIY: Build Your Own Cold Frame
A cold frame is a useful tool that every gardener can benefit from. It can be used to jump-start your garden in the spring and to extend your harvest season in the fall. This enclosure helps to protect your plants from adverse weather conditions, particularly excessive cold or dampness and it creates a microclimate for starting seeds as well. The cold frame has a clear top that allows sunlight in and while there are expensive kits that you can purchase for a more substantial enclosure it can be made from simple materials including hay bales or cinder blocks. My father made one many years ago out of scrap wood and an old window frame.
If you are interested in building one for your garden here are some useful tips to get you started:
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Don’t “Blow Your Cover” - The most important part of your cold frame is the cover that allows light to get into the enclosure. You can use glass, fiberglass or plastic such as a shower curtain but it must be transparent. You can use an old window like my father did but be sure that the wood isn’t rotting or that the paint isn’t flaking. Gardeners in extreme Northern climates may want to avoid glass which can break under the weight of heavy snow. It is also important to make sure your cover slopes from top to bottom so rain can run off of it. This slope will also increase the amount of sunlight that gets into your cold frame.
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Pick the Right Location - Your cold frame will perform best if it faces South otherwise it may not get enough sunlight to heat up the enclosure. If you can’t find a Southern exposure than you can try a Western or Eastern one. If your only choice is a Northern Exposure you may need to consider an additional source of heat. Insulating your cold frame is also another way to ensure you retain heat in the enclosure. This can be as simple as piling soil or leaves around the outside of your cold frame.
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Don’t Forget About Ventilation - You’ll be surprised at just how hot it can get inside of a cold frame. It is often necessary on particularly warm days to open the lip to allow temperatures to moderate or you could cook your plants! More sophisticated cold frames have automatic ventilation systems which are triggered when a certain temperature threshold is reached. When outside temperatures are over 45 degrees you’ll want to use a stick to prop open the top but don’t forget to close it before the sun goes down in the afternoon!
So what can you grow in a cold frame? The answer is pretty much anything you like! In the fall you can plant Spinach, Lettuce, Kale and other greens that you can harvest into the fall or even the winter. In the March or April, you can plant warm weather vegetables such as Peppers and Tomatoes to get a head start on the growing season and as a result a much earlier harvest.
If you’ve never used a cold frame you may want to consider installing one in your yard. It is a great way to allow you to garden outdoors almost all year round!
