The Coldframe Page

A coldframe is a mini green house. They can extend the growing season considerably. Growing more food over a longer season means not having to store or buy so much. The growing season is extended further into the Fall and starts earlier in the Spring.

There are many kinds of coldframes. I have two fixed and one mobile. One is located along the 25 foot south facing glass wall of the sun room. It is about 2 1/2 feet wide and 2 1/2 feet high. Its cover is corrugated fiberglass sheets, two screwed together lengthwise making it 8 feet by 5 1/2 feet. The frame is two curved half inch PVC pipes. One end in the ground 4 or 5 inches, the other fitting over a nail sticking out of the wood window frame, see below.. The shape is a very pleasing curve making a distinctive art deco effect. I used to have a more typical angled glass top but the Fiberglas is much lighter and the volume inside much greater so broccoli and other knee high plants can grow at the front. There are wooden side pieces at each end of the coldframe. The fiberglass cover comes off easily during the summertime as it is connected to wooden runners with only two screws.

I am learning how to manage the coldframe. Bush beans are way ahead of the normal season as were broccoli, cauliflower, peas. Early season veges can grow in the coldframe and then be transplanted out. Tomatoes, summer squash, cukes have a major head start. I am trying eggplant, watermelon and cantaloupe. In mid summer, I will plant new tomatoes and cukes and others to see how I can extend the season for summer veges into the Fall. I will also put in cooler season veges mid August. Lots of experimenting. Its fun to work with the plants and a low tech [minus fiberglass] semi artificial/solar environment.

Out front is a sunken coldframe. It is a bit over 7 feet long 3 feet wide and 3 feet deep at the bermed up back side. The front is a bed 18 inches above the low point and 8 inches below ground level. The entire cold frame is all boxed in with salvaged wood. The lid is a 2 x 2 frame with corrugated fiberglass screwed into the frame and hinged.

The micro climate created is considerable. I had a live tomato plant all winter. It was not producing but it did survive "outside" temps into the low 20's with a leaky lid. It could be much tighter. This frame definitely accelerates the season with lettuce, beets, chard, tomatoes, summer squash, cuke all advanced over in the yard locations. The sunken coldframe is less than a year old so I am learning how to manage it best. I am quite interested to see how I can extend the season for tomatoes, squash and cukes. Winter veges also will grow much more readily.

Finally, a single or double piece of corrugated fiberglass bent into a rainbow shape makes a simple and effective cloche/coldframe. Beans, lettuce, kale all benefit from the warmer space. A single sheet can accommodate two rows of veges until they outgrow the space. An added benefit is that for early spring planting, the ground around the plants can be kept dry. In the NW, this is helpful because dry ground is less attractive to slugs and snails. Covered up means less havoc from gastropods.

Coldframes are a gardening tool with great value. They can be adapted to all kinds of spaces with a variety of designs with odd sorts of recycled materials. Add some manure of fresh compost at the very bottom, cover with several inches of soil and you have a heated coldframe, or hot frame. Good luck!

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