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In the winter, a coldframe offers protection to less hardy plants and newly started perennials. It is an ideal location for overwintering hardy bonsai. It simplifies the storage of bulbs and plants for mid-winter forcing indoors. In early spring, a coldframe is useful for hardening off seedlings that were started indoors or in a greenhouse. This hardening off period is very important as seedlings can suffer serious setbacks if moved directly from the warmth and protection of the house to the garden. They need a transition period in which they are given protection from sudden drops in temperature in order to gradually adjust to the outdoor climate.

The principle that makes one of these unheated frames such a useful structure for much of the year is the collection of heat from the sun's rays through the sash. To maximize collection of the sun's rays, the ideal location for a coldframe is a south or southeastern exposure with a slight slope to insure good drainage. A sheltered spot with a wall or hedge to the north will provide protection against winter winds. To simplify using a coldframe, include a walkway to the front of the frame, adequate space behind the frame to remove the sash, and easy access to water.

Management of a coldframe is quite simple if a few basic rules are followed concerning ventilation, watering, and protection from extremes in temperature. Ventilation is most critical in late winter and early spring on clear, sunny days when temperatures rise above 45F. The sash should be raised partially to prevent the build up of extreme temperatures inside the coldframe. As the season progresses, the sash can be raised for longer periods each day until it is finally removed for the summer. The sash should be lowered or replaced each day early enough to conserve some heat for the evening. Watering should be done early in the day so that plants can be dry before dark to help reduce disease problems.

moon phases
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