Stephen Albert
A cold frame can help you extend your growing season by capturing the warming rays of the winter sun and holding them. Even the simplest cold frame can lengthen your growing season by several weeks. To get the most out of your cold frame give some forethought to the site where it will best perform. Here are some tips for situating your cold frame:
• Most sun. Site the frame where it will receive sun from mid-morning to mid-afternoon in the winter and early spring.
• Face south. Site the frame so that it faces south, southwest, or southeast; this will ensure the greatest exposure to solar heat during the winter months when the sun tracks furthest to the south. (For those of you who live in the Southern Hemisphere, site the frame to face north.)
• Size of frame. The back wall of the frame should be at least a few inches higher than the front wall so that the top or sash is angled and receives maximum sun exposure. Commonly, the front of the frame is 4 to 10 inches lower than the back side allowing for the maximum sun exposure.
• Easy access. Site the frame where it is easy to monitor, not far from the house. Like all of your vegetable garden beds, the beds (and plants) that get the most attention are likely to be the most bountiful.
• Level ground. Site the frame on level, well-drained soil. Water should not be allowed to sit in or around the cold frame. If you must situate your frame on slope, be sure that water from up the slope drains away from and not into the frame.
• Near water. Site the frame near a source of water. Plants growing in the cool time of the year require less water, but still require watering. Keep the soil or growing medium just moist but not wet.
• Good soil. The open bottomed frame should be sited over good soil or a raised bed. If the frame is permanent prepare the soil as you would any other vegetable-growing bed. Amend the soil in the frame just as you would other vegetable-growing beds, adding a layer of compost twice a year. If the frame is portable, prepare the bed and amend the soil before you set the frame in place for the winter season.
• Protect from wind. Site the frame where it is protected from prevailing winds; place the frame to the south of a building, wall, fence, or hedge. Wind will rob the frame of stored solar heat. Plants exposed to wind can be damaged or robbed of moisture.
• Out of shade. Site the frame where it is not shaded by buildings or evergreen trees. A frame for winter use may be sited near deciduous trees which will be bare of leaves in winter. Maximum exposure to the winter sun is important.
• Capture reflected heat. Site the frame against a building or wall where heat and light will bounce off the building or wall and into the frame.
