Cold Frames  For Season Extension

Extend Your Growing Season

There’s no need to let your garden stay empty during the winter. Instead
of clearing off an empty patch of soil in April, why not enjoy a garden full
of ready-to-eat spinach? Cold-hardy crops planted in your cold frame in
late fall will grow slowly through the winter and be ready to harvest as
soon as spring arrives.

The growing season in New England is short- typically lasting from the
beginning of April through the end of October, a total of just seven
months. Anything that can prolong this short season, even if just for a few
weeks is a welcome reprieve from the threat of cold winter days. An
average growing season is 32 weeks. With season extension tools, the
season can be extended to up to 41 weeks.

Cold Frame Technology

Cold frames act as miniature greenhouses and sit on top of your raised bed frame or directly over an in-ground garden. The plastic-lidded frame traps the sun’s rays, warming the air inside the frame up to 30 degrees more than the outside temperature. The lid is attached with a movable
arm, which is filled with wax. As the sun shines upon the frame, the wax warms and expands, pushing the arm and opening the lid to vent, which prevents the air from becoming too jot and scorching the plants. This is critical to promote healthy growth and keep plants alive in the spring and fall, allowing for the highest possible success rate without constant monitoring.

Growing in a cold frame is different than growing food at any other time of the year. In the fall, the weather is usually cold and there are far fewer hours of sunlight. The plants that do best in these conditions are cool weather crops, some of which might survive a hard frost.

Cold Frame Crops

Plants that can be harvested into the late fall with a cold frame:

  • greens: lettuces, kale, collards, chard, and spinach
  • broccoli
  • hardy herbs
  • carrots
  • beets
  • radishes

Plants that can be seeded in late fall for overwintering with a cold frame:

  • beets
  • carrots
  • kale
  • spinach
  • scallions
  • hardy winter greens: claytonia, mache, and sorrel


Green City Grower’s cold frames cost $540 per 4’x4′ cold frame. This includes free delivery and installation in eastern MA. If you are interested in purchasing a cold frame, reach out! 617-776-1400 or info@greencitygrowers.com

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