No matter how long the gardening season, it always seems to fall a bit short. Frame gardening is one way that many gardeners extend the growing season for a variety of flowers and vegetables. To make a cold frame, construct a bottomless box and set it in the garden or atop other good soil in a sunny location. Frames are usually made from scrap lumber, but concrete blocks or bricks can also be used. Top the box either with glass (perhaps an old storm window) or a frame covered with clear plastic. Hinge the cover so it may be opened for ventilation on warm days.
Gardeners use frames to “harden off” seedlings that were started indoors or to start their vegetable and bedding plants from seed. Sow seeds of crops such as radish, lettuce, endive, and scallions directly in the frame for an early or postseason harvest. You can even raise them there all summer as long as the cover is removed when warm weather arrives.
Cold frames can also be used to good advantage for over-wintering potted herbs and perennials or for holding cuttings of woody plants taken during the summer. The trick to winter framing is insulation. Cover the plants and cuttings in the frame with salt marsh hay or straw, then cover the glass with plywood or a thick tarp to keep out light and prevent snow damage.
A hot bed is a cold frame that is heated. This can be accomplished with electric heating cables, but the old method of using horse manure or compost works quite well and is more economical. For a nonelectric hot bed, excavate 18 to 24 inches under the frame and add manure or compost. Turn and moisten this material every couple of days for a week until it settles, then cover it with 6 inches of soil. As the manure or compost decomposes, it will generate enough heat to protect against early or late frosts.
Temporary frames or “cloches” can be made by leaning old storm windows tent-style over the plants along the length of the garden row. To protect individual seedlings or small plants, cut the bottoms out of plastic milk jugs and place them over individual plants, holding the jugs in place with mounded soil. During sunny days, remove the caps for ventilation.