Cold Frames:

                         A cold  frame is basically a low cost, simple mini-greenhouse that allows
                         you  to create nearly year around conditions for plant  growth without
                         spending a fortune.  For example, even though you may love salads,
                         freezing temperatures force you to stop growing lettuce, spinach,
                         carrots, and other salad crops by the middle of October or November
                         or delay your  spring crop by several weeks.
                         With a cold frame, you can extend the growing season at least another
                         45 days or so, even if there is snow on the ground.

                         Although you can buy a commercially made cold frame, it's fairly
                         easy to construct one.

(The first commercially   made one I ever bought.This year will be its test year! Photo by Floyd Gardener)

                         Anything easier than stacking a few bales of hay or straw?
                         It doesn't have to be fancy, just functional, right?.
                         You'll need between four and eight bales of  hay or straw, depending on
                         how large you want your cold frame to be and you are also
                         going to need a lid.
                         A frame can be constructed from six bales of straw and a  sheet of
                         Plexiglass, although you can use an old window frame or an
                         old glass door.
                                                        
(My simple, low-cost, nearly year'round cold frame; that's spinach and the photo was taken in January!)

                         The soil beneath the cold frame should be dug to a depth of eight to 12
                         inches and amended with compost. It should slope in such a way that it is
                         higher in the back than the front by about 10 inches. Ideally, the cold
                         frame should be located in full sun and face the south. Place the frame
                         against a north wall, a fence, or a row of trees or shrubs that will offer
                         protection from howling winds.

                         The reason the bed needs to slope from back to front is that you want
                         the maximum amount of light to reach inside the cold frame. During the
                         spring and summer, the lid should slope 35 to 45 degrees, but a
                         55-degree slope catches the most light in the fall.

                         To assemble the cold frame, create a rectangular box with the bales of
                         straw, making sure you get a tight fit between the bales, and set the lid
                         on top. After a season or two of growing and it is time the replace the
                         straw in the cold frame, the old straw can be used as mulch in your
                         garden.

                         Cold frames are ideal for hardening off flats of tender young annuals or
                         perennials, and for storing root cuttings. For those of you who like to force
                         spring-flowering bulbs to bloom indoors, most of those bulbs will first
                         have to be chilled from six to 14 weeks. Most books suggest that bulbs
                         be placed in the refrigerator, but using a cold frame you can actually pot
                         those bulbs, bury the pots up to their rims with soil, and leave the lid
                         propped open so just enough cold air gets in.

                         Temperature control is probably the most important thing to keep in mind
                         when growing in a cold frame because even in the middle of the winter, if
                         the sun is bright, temperatures inside the cold frame can climb quickly to
                         100 degrees or more. That much heat will kill the plants inside, so a
                         thermometer placed inside the cold frame is a must.

                         Monitor the temperature inside the frame daily, and when temperatures
                         rise above 80 degrees, vent the frame by propping the lid approximately
                         six inches. Keep checking the temperature, until it is between 45 and 75
                         degrees, which naturally depends on the crop you are growing. Before
                         sundown, you should close the lid, and if temperatures are expected to
                         drop below freezing, throw a blanket over the cold frame to hold the heat
                         in. You may also consider placing plastic milk jugs filled with water on the
                         north wall of the cold frame. The water absorbs heat during the day and
                         releases it at night, thereby stabilizing temperatures overnight. The jugs
                         will absorb even more heat if they are spray-painted black.
 

                        Cold frames can also be built with wood or metal sides. If you use wood for constructing the coldframe, treat it with a preservative. Sidewalls can be as high as needed for convenience; however, to keep heat loss to a minimum, 8- to 12-inch sides are usual. Make the north wall taller than the south for better sunlight exposure. Place the coldframe in an area reasonably protected from wind where it will receive all possible sunlight during the winter. Cover the top of the coldframe with clear plastic, fiberglass, or glass sash. During sunny and warm weather, raise the cover for ventilation throughout the day and then close the cover at night.

Plants can be grown in coldframes or hotbeds either in prepared soil within the frame or in pots or flats placed in the frame on sand or gravel. Supply the necessary drainage by placing a 6-inch layer of gravel below the frame. If you use heating cable, place it in sand for best heat diffusion. Prevent damage from digging by placing a layer of screen or hardware cloth an inch or two above the cable.

 
Coldframes can be used to start flower and vegetable plants before outdoor planting, and to grow some of the hardier vegetables during the winter. Lettuce, chives, parsley, carrots, green onions, kale, and radishes, for example, can be grown in a cold frame during mild winters.

HOT BEDS:
                         There is something called a hot bed that is structurally identical to a cold frame.

                   Hotbeds are coldframes with an added source of generated heat. They can provide much the same growing environment for plants as a greenhouse. They do require more attention to ventilation requirements than coldframes, since the heat source needs regulation.

Hotbeds usually are heated by electric soil heating cables, steam or hot water pipes, or by placing the hotbed over 12 to 24 inches of animal bedding and manure. The decomposing manure gives off heat; however, this is difficult to regulate and may not supply a constant source through the entire season when heat is needed.

Hotbeds should be lined with moisture-proof insulation. Maintain a temperature of 50° to 70°F. If you use electrical heating cables as the heat source, provide 10 to 15 watts of electric heat per square foot of growing area. Soil-cable thermostats are available at supply houses, and may come with the cable. Automatic temperature and ventilation controls will help provide more effective heat and ventilation control. A small thermometer placed inside the box will help determine when to open for ventilation to prevent excessive heating.

Hotbeds usually are constructed with sidewalls 8 to 16 inches high and a top cover of plastic, fiberglass, or glass.

NOTE: Wood members should be treated with a wood preservative containing copper sulfate, such as cuprinol or copper napthenate. Apply it with a brush or spray. Do not use wood preservatives containing pentachlorophenol or creosote, as these products will damage plants. Coat all the wood with preservative, and air-dry for a week before placing plants inside.

Use weatherproof wire for all hotbed wiring. Use approved terminal equipment, and follow safe wiring practices in conformance with local wiring codes. Heating cables are designed to operate on either 110 or 220 volts. Small beds can be heated satisfactorily on the lower voltage.

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