Grow: Primers & Projects
Fancy or simple, a cold frame makes a great "halfway house" for rearing your senstive seedlings
Not to be confused with a hotbed an artificially heated frame a cold frame is a great natural way to "harden off" seedlings that you've started indoors. By hardening off we mean giving the seedlings a little tough love, preparing them for the harsher conditions of the outside world beyond the greenhouse. Great for collecting warm sunlight and providing protection and ventilation all at once, cold frames can be thought of as halfway houses for your young plants before they move out on their own into the garden.
Another benefit is that when using a cold frame you can start this process as early as four to six weeks before your growing zone is officially frost-free. Thus a cold frame serves to extend the vegetable season. All closed up you can also use it as a part-time greenhouse or, with the top open or removed, even a spare vegetable bed.
At The Victory Garden we have an industrial-size cold frame our gardener Kip Anderson recently rebuilt based on an old design by host Michael Weishan's father. It has plastic roof panels that capture sunlight and retractable legs that let us raise the panels and set them in place to give the plants some air, as well as easy access for the gardener.
Buy a Portable Cold Frame
But there are also other, simpler cold frame options available for gardeners in small spaces. One is a portable "mini-greenhouse" that can double as a cold frame. Available by mail order, as well as on the Internet and garden centers, these are typically made of a combination of lightweight metal framing and plastic. This gives them great flexibility of use and makes for easy storage in the off-season. The German-made example Michael demonstrated on the show cost about $100 through a mail-order gardening catalog.
Or 4 Hay Bales + 1 Window Frame ... and Presto
Another and even cheaper option is to build a simple, more or less "old-fashioned" cold frame yourself, using four rectangular bales of hay and an intact window frame. Arrange the hay bales so that they form a square with a space in the center of a size that can be covered by laying the window frame flat on top. The hay will provide insulation and the window frame will let in light. Just remember when it's sunny to prop the window open with a brick to provide adequate ventilation (so you don't "cook" your plants), and don't forget to water.
After a little while in the nourishing environs of the cold frame, your
plants will be "all grown up" ready to make it on their own out in the
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This segment appears in show #2701.