A Simple DIY Cold Frame

During the 2022 season we completed the final touches to our One-Story Greenhouse.  Because it took longer to finish than anticipated, we won’t be able to talk about starting Fall seedlings for the garden 🙁.  An additional feature under consideration is a solar heater.  We’ll see.

To compliment the greenhouse we are building three cold frames which should be ready by spring 2023. These will allow us to harden-off seedlings produced in the greenhouse. The cf can also be used to extend the fall season for spinach, lettuce, kale, etc.  There’s nothing better than fresh greens when little else is going on in the garden!

The design of the cold frame (cf) is simple and made of plywood and topped off with an old window purchased at Habitat for Humanity.  Cement pavers serve as the cf’s foundation to preserve the integrity of the plywood, reduce weed growth, and act as collectors of radiant energy.

The plywood’s exterior surface is painted with two coats of water soluble exterior black paint to help preserve the wood and perhaps absorb a little heat.  The windows are sanded, glazed and painted with two coats of latex exterior white paint (both sides) and attached to the cf with two door hinges.  The interior plywood walls are also painted with two coats of latex exterior white paint to preserve the wood structure and reflect light within the cold frame.

If you’ve never used a cold frame please be aware that they can turn into ovens when the sunlight pours through the glass.  Let’s just say that I’ve burned up a few plants over the years.  Even with temps in the 50F’s, a closed up cold frame can fry your plants! Simply prop open the window, in the morning, and all should be well.  You may want to place a thermometer in the cf so that you can monitor its internal temp.

Although we’ve elected to publish this post prematurely, we promise to provide updates, measurements, pics, etc.

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