Cold Frames.

Cold frames, sun boxes, and hot beds are relatively inexpensive, simple structures for providing a favourable environment for growing cool-weather crops in the very early spring, the fall, and even into the winter months.

Cold frames and sun boxes rely on the sun for their sole source of heat. Hot beds are heated by soil-heating cables, steam-carrying pipes, or fresh, straw manure buried beneath the rooting zones of the plants.

A sheltered spot with a wall or hedge to the north will provide protection against winter winds. Sinking the frame into the ground somewhat will also provide protection, with the earth for insulation.

The ideal location for a cold frame is a southern or south-eastern exposure with a slight slope to insure good drainage and maximum solar absorption. Heat is collected by sashes these sloping frames allow the sun’s rays to penetrate; the sashes are made of clear plastic, glass, or fibreglass.

Some Cold Frames are sometimes made lightweight so that they can be moved around the garden easily ore another possibility is a Dutch light, which is a parable greenhouse, depending on the size of your cold frame you may want to put a walkway around the frame in order to raise the sash.

In early spring a cold frame is useful for hardening off seedlings that were started indoors or in a greenhouse. This hardening-off period is important, because seedlings can suffer serious setbacks if they are moved directly from the warmth and protection of the house to the garden. The cold frame provides a transition period for gradual adjustment to the outdoor weather. It is also possible to start cool-weather crops in the cold frame and either transplant them to the garden or grow them to maturity in the frame.

Young seedlings of hardy and half-hardy annuals can be started in a frame many weeks before they can be started in the open. The soil in a portion of the bed can be replaced with sand or peat moss or other medium suitable for rooting cuttings.

Cold Frames are also good for sowing some cool-weather crops, If provided with adequate moisture and fertilization, most cool-season crops will continue to grow through early winter in there protected environment, Depending on the harshness of the winter and whether or not additional heating is used, a cold frame may continue to provide fresh greens, herbs, and root crops throughout the cold winter months.

Building a cold frame.

A cold frame can be built from a variety of materials; wood, brick, and cinder block, If wood is preferred, choose a species that will resist decay, such as a good grade of cedar, or use pressure-treated wood. Never use wood that is treated with chemicals such as creosote, pentachlorophenol, because these substances are very harmful to growing plants.

You can purchase kits for your growing frames these are easy to assemble; some kits even contain automatic ventilation equipment. Really there is no standard size for your frame; I usually build to the dimensions of the sash, being it glass or plastic or fibreglass. And the other thing to take into consideration is available space you have.

Do not make the structure too wide for weeding and harvesting: 4 to 5 feet is about as wide as is convenient to reach across. The sash of the frame should be sloped to the south to allow maximum exposure to the sun’s rays.

Protect against sudden cold snaps by insulating, a simple method is to throw sacks filled with straw or leaves over the sash on the frame at night, and straw bales staked against the frame.

Ventilation is most critical in the late winter, early spring, and early fall on clear, sunny days when the temperatures rise above 45F. The sash should be raised partially to prevent the build up of extreme temperatures inside the frame. Lower or replace the sash each day early enough to conserve some heat for the evening.

In the summer extreme heat can be a big problem intensive sunlight can damage your plants, to avoid this, shade with lath sashes or an old bamboo window blind. Try to water in the early part of the day so that plants dry before dark to reduce disease problems.