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Cold Frame vs Greenhouse

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Cold frame vs greenhouse – which is better? What do you need to grow vegetables, fruit and herbs year ’round?

Which Is Better, a Cold Frame or a Greenhouse?

I grew up in a suburban/urban environment. My dad built a greenhouse in the backyard. It was a lean-to greenhouse he added to the side of the garage. My mother’s prized Blaze climbing roses and rock garden were sacrificed to the addition of the greenhouse, but the greenhouse was my father’s pride and joy.

He didn’t grow vegetables in there during the winter, but he did overwinter many of his plants, such as geraniums (which I bring indoors) and many others. He started vegetable flats in the spring and his precious chrysanthemums, too.

Many years later, when I moved to a small apartment with yard privileges, my husband built a small cold frame for me. It sat on the earth in the rear of the garden. I could overwinter some tender herbs, such as rosemary, in my little cold frame.

Cold Frame Definition

A cold frame is a wooden box with a plastic or glass lid on top. The lid is slanted to increase the sun’s power. It warms the interior of the box. Plants are placed inside the box, and the lid is opened or closed to allow air and heat to escape. Although not as warm as a greenhouse, cold frames can protect plants from frost.

What Is a Greenhouse?

A greenhouse is a structure designed to create a controlled environment for growing plants, typically made with transparent materials like glass or plastic that allow sunlight to enter while trapping heat inside. This enclosed space helps maintain a stable temperature and humidity level, which promotes plant growth even in unfavorable weather conditions.

Greenhouses are commonly used in agriculture and horticulture to extend growing seasons, protect crops from pests and frost, and optimize conditions for delicate or exotic plants. They can range in size from small backyard setups to large commercial facilities.

Pros and Cons of Cold Frame vs. Greenhouse

Cold Frames – Pros

  • Easy to make
  • Inexpensive
  • Small so good for small spaces and yards
  • Great for overwintering hardy annuals and herbs or hardening off seedlings in the spring

Cold Frames – Cons

  • Not warm enough to protect tropical plants or very tender annuals
  • It may be difficult to regulate the temperature (too warm or too cold)
  • Set on the ground so you will have to bend or crouch to work with your plants

Greenhouses – Pros

  • Large, roomy, sunlit – perfect for avid gardeners, for starting seedlings or for growing tender plants all year round
  • Benches keep plants at a good height to work with, so that you do not need to crouch down to tend the plants
  • Adds a large space for gardening to your home or yard

Greenhouses – Cons

  • Expensive to build. Even a simple stand-alone greenhouse costs $500, $1,000, and up
  • Expensive to maintain. Greenhouses require regular maintenance.
  • Works best with electricity (to automatically open and close vents), which requires additional costs and an electrician to run the line to the site.
  • It may be too big for a small-scale gardener to handle.

Start Small: Cold Frames

If I were learning to garden again and I wanted to expand into three or four-season gardening, I would start with a cold frame.

Hoop Houses or High Tunnels

Hoop houses or high tunnels made from PVC or wire frames and heavy-duty plastic make fine cold frames. I convert my raised beds into cold frames by adding a heavy, repurposed window (salvaged from a school being remodeled) and placing it over the bed. A board, a brick or two, and it’s at the perfect angle to act as a mini greenhouse.

Keeping Cold Frames Warm with Manure (Hot Frame)

Gardeners who have ready access to horse or cow manure from a family pet or farm animals can even add the fresh manure to the bottom of the cold frame to create what is called a hot frame. Decomposing horse manure generates a lot of heat. In olden days, farmers used horse manure-lined cold frames to keep tender annuals and vegetables growing well into the fall and winter. Depending on your climate and circumstances, you may also be able to try this.

More Information from the Cooperative Extension Office

If you’d like to explore building cold frames and hot houses, I’ve created this list to help you find plans and more information from great sources. Leave a comment on the blog to let me know if you’ve built your cold frame!

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