Build a Cold Frame for All Seasons

Enlarge Image Image Gallery You can sum up the virtues of this innovative cold frame in one word: security. PHOTO: WILLIAM WALDRON

Feeds a family of four from just 18 square feet! 

Shakes off the deep chills of December, ignores the moodiness of March, scoffs at scorching August afternoons! 

Can be built in a half day by any preliterate four-year-old (with a little help from Mom and Dad)! 

OK, OK, maybe MOTHER's versatile four-season cold frame isn't really that good. But I've been gardening for 15 years and have seen and made my share of cold frames. (The first one I built was a primitive wooden box I stuck a foot deep in red clay. I came back after the first rain to find a box of water that didn't drain for days. Plants never entered its domain.) I've learned enough by now to know what features I'd want a good cold frame to have—and I think I've come up with a design that will suit most other gardeners as well.

Let's face it: The basic open-or-shut cold frame is a tricky fellow to operate. Open it up too early in the morning, and you're liable to nip the life out of those tender spring seedlings; leave it closed too long when the sun's out, and you're just as likely to cook 'em crisp.

Fortunately, I've figured out how to build a cold frame that tackles those problems: by offering more options than just wide open or shut tight. Instead, it has four settings: first position—that's completely closed, with the glass cover flat on the box. Second position—that's with the glass lid lifted partway up at about a 30º angle. Third position—the cover's now a good bit higher, at about a 60º angle. And fourth—that's with the cover swung all the way off the frame. Oh, then there's completely closed with the attached insulated cover down too—for an extra, fifth, position, to keep plants cozy on cold winter nights.

These options offer a variety of advantages. Most cold frames are built either for spring/fall or for winter use, the latter having a much steeper glazing angle to make better use of low winter sun. I didn't want a frame that was good for only one season. This one, when open to the steeply angled third position, is great for absorbing winter sun; when dropped halfway down to second position, is angled well for spring and fall.

Adding an attached insulated cover opened up even more options. First, it gave me many nights of sound sleep because I wasn't worrying about how low the temperatures had dropped or if I had laid enough blankets on top of the frame. Second, because it's attached, I'm much more likely to use it. (Otherwise, I'd probably be asking my wife every chilly evening, "Susan, did you see where I left the cold frame cover?") And third, because the inside of the cover is white, it can reflect extra light into the plant box when the glazing's in first, second, or third position.