Cold Frame Gardening

comments (9) August 13th, 2009

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With a cold frame like this, you can grow greens and other cool-season vegetables right through the winter.
Download plans, a materials list, and instructions for building this cold frame.
Sown the first of August, these carrots are eating size by the time the snow flies. Protected by a layer of straw, theyll stay crisp and sweet all winter.
With a cold frame like this, you can grow greens and other cool-season vegetables right through the winter.Click To Enlarge

With a cold frame like this, you can grow greens and other cool-season vegetables right through the winter.

Photo: Ruth Lively

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Like most vegetable gardeners, I’ve always been interested in extending the har­­vest beyond the confines of “the growing season.” Along with the prolonged enjoyment of puttering in the garden, I treasure the reward of continuing to eat fresh, home-grown food. The easiest and most economical way to do this is with a cold frame.

If, like me, you’re not ready for the gardening year to end with the season’s first hard frost, then maybe you’re ready for a cold frame, too. This simple bottomless box with a removable glass or plastic lid protects plants inside from excessively low temperatures, wind, snow, and rain. In doing so, it creates a microclimate that is a zone and a half warmer than your garden. My garden may be in Maine, but the plants in my cold frame think they’re in New Jersey. A cold frame in New Jersey provides Georgia weather. The result is a harvest of fresh vegetables all winter long.

  Why all this talk about winter crops when you’re still waiting for the first tomato?
Because you can’t wait until winter to plant the winter garden. The rate that plants grow diminishes with the shortening days of fall until it almost stops. By then, the plants need to have reached harvestable size. After that, they’ll hibernate successfully in the shelter of the cold frame.

I start sowing seeds in my cold frame mid-July (see A cold frame timetable), but that's because I live in Maine. You'll need to adjust your planting schedule for your local climate.
   
I began serious exploration of winter cold-frame gardening back in 1981 when I took the job of farm manager at a private school in Vermont. The program was supposed to supply the school with food while engaging students in a hands-on way. The problem was, there wasn’t much overlap of the gardening year and the school year. To involve students in fresh vegetable production, it would have to happen in winter. And if winter horticulture were to catch on with teenagers, it would need more charisma than a Brussels sprout. A large, heated greenhouse was out of the picture, and so I turned to cold frames.

Bottomless box with a skylight

The beauty of a cold frame is that it’s simple. Mine would have been familiar to a gardener a hundred years ago. Each one is a bottomless box made of 2-in. thick planks, 12 in. high at the back and 8 in. high at the front, and covered with glass frames, called lights.

  Get cold frame plans
Download plans, a materials list, and instructions for building this cold frame.
 
The back of the frame is cut higher than the front so the angled lights can catch the slanting winter sun. I site the frames with the lights sloping toward the south in a spot where they will have as much winter sun as possible. Some shade is tolerable, but full sun is best.

If you have access to old storm windows, you can use those as lights. If you don’t want to build your own frame, however, you can buy a sturdy ready-made polycarbonate-glazed cold frame for a few hundred dollars (companies that sell cold frames include Charley's Greenhouse & Garden and Peaceful Valley Farm & Garden Supply).

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posted in: Projects, fall garden, greens, cold frame

Comments (9)

Sweet_Potatoes writes: Remember to use water storage for heat release at night.
Plastic jugs with black-dyed water.
Posted: 2:02 am on July 21st
Piterson writes:
nice work . I like it,Very interesting article, Anothony. You've got me hooked up - keep up the nice work!
http://www.dafplumbingandheatingservices.co.uk/

Posted: 1:25 am on July 5th
Sweet_Potatoes writes: The R factor of one pane of glass is 1.
Put two panes together and get R of 1 1/2.
Separate the two panes by 1 1/2 inches -
which is optimum - and get R of 3. So the
air space is important.
The R of plastic sheet is zero, but I've
used plastic with glass and it gave an
increase.

Posted: 2:32 pm on June 8th
vladsbtch writes: I am going to try to make one for this winter. Here in Nashville,TN I should have a good crop!!! Thank you for sharing!!
Posted: 8:00 pm on July 16th
bilili_3 writes: I am going to build a cold frame within the next few weeks. Got to start planning what I want to plant so I can order the seeds now while they are in stock. I love this idea and I bought Elliot's book on the subject which I strongly recommend.

Posted: 7:22 am on April 22nd
LeslieinPayson writes: I have some supports for my tomatoes which are about 4 ft. above a raised bed. I was thinking about covering them with heavy plastic for a sort-of cold frame. The plastic would be straight across the top. Will plastic likely be enough insulation? We are in an area tha gets down to 20s and even teens in mid-winter, but the days are often 50s and the ground never freezes. I'm figuring I will need to open the sides of the frame many days.
Posted: 1:33 pm on August 14th
RuthHenriquezLyon writes: Thank you for this article; it's the best I've read so far, especially as concerns types of plants to grow in winter, plus when to plant them, and how to manage them in the frame. I'm looking forward to trying it out.
Posted: 9:03 pm on May 29th
badlandskid writes: I use discarded glass bathroom shower doors for my cold frame. They are quite sturdy. And I add a light bulb for extra heat.
Posted: 12:30 pm on March 20th
badlandskid writes: Perhaps you could increase the insulation effect of the plastic by applying it double with an airspace between just like double glazed windows for house.
Posted: 12:24 pm on March 20th
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