A cold frame is simply a miniature greenhouse -- a bottomless box, usually constructed of scrap lumber, recycled plastic or straw, and topped with a glass or plastic cover.
In autumn, fresh parsley, basil and other herbs will grow in the frame past Thanksgiving, while lettuces and greens such as tender Bibb, butterhead, looseleaf and arugula, in addition to radishes, spinach, kale, broccoli, leeks and cabbages, can continue to thrive well into December.
In winter, cold frames can be used to force spring flowering bulbs to bloom.
In early spring, a cold frame can be used to start seeds and "harden off" or acclimatize annual flowers and vegetable seedlings to the great outdoors.
Cold frames are best located in full sun facing south. Placing the frame against a fence or a row of shrubs will offer additional protection against the elements. All cold frames are bottomless and can be set at ground level, or the soil beneath the cold frame can be dug 8 inches to 12 inches deep for added protection.
Cold Frame - Bales Of Hay
An inexpensive "instant" cold frame can be created by using six bales of hay (about $12 each, available at garden centers). Simply create a rectangular box with the bales of hay, making sure you get a tight fit between the bales.
(After a season or two of use, the straw will have to be replaced; the old straw can be used as mulch in your garden.)
In the planting area in the middle, place pieces of weed-blocking material on the bottom, add a thick layer of pea gravel or pebbles for drainage, then a generous layer of top soil amended with compost (or use potting soil).
The cold frame is now ready to start seedlings or to protect tender plants. (lettuce, spinach, chard, herbs, etc.) Place a piece of Plexiglas (about $24 for about 3-foot-by-6-foot piece) or an old storm window over the cold frame. On warm, sunny days, it may be necessary to prop the lid open or remove the cover, replacing the cover in the evening as the temperatures cool.
Cold Frame - Easy Do-It-Yourself
A simple cold frame (not fancy but functional) can be created by using a "raised garden bed kit" from a mail order supplier such as Recycled Plastics Marketing (RPM). The company can be reached at 800-867-3201, and its Web site is www.rrpm.com. RPM's kit is made from recycled plastic bottles. (Be sure never to use treated wood when making a raised garden bed as the toxins can leach into the soil.)
The raised beds come in various sizes -- and prices. In her demonstration on The Saturday Early Show, Raimondi is using a 4-foot-by-4-foot kit, which cost $129. This kit assembles in minutes: Lay boards on flat level and align notches for each corner. The tongue-and-groove design keeps the boards aligne.
Hammer a 4-foot garden stake into the ground in each inside corner of the bed at a 45 degree angle, forming an A-frame. Then place a 4-foot cross member-stake across the top of the A-frame. Anchor the cross-sections with garden twine. (Stakes cost about $1.70 each.)
Drape heavy-duty clear plastic sheeting (comes in various size rolls available at hardware stores) over the A-frame. Staple back and sides to frame.
Staple a garden stake to the bottom of the front panel to create a moveable flap which can be rolled back to allow access for planting or to be raised during warm, sunny days.
Follow planting direction as per "Bales of Hay" cold frame.
In very cold climates, for extra protection, lay pine branches or build soil around the outsides of bottom of cold frame.
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