Cold frame vs greenhouse – which is better? What do you need to grow vegetables, fruit and herbs year ’round?
Cold Frame vs Greenhouse
I’m a kind of unusual person in that although I grew up in a suburban/urban environment, my dad built a greenhouse in the backyard. Seriously, a greenhouse. 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 winter over many of his plants: geraniums (which I bring indoors) and many others. He started countless 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 – rosemary, parsley, mint – in my little cold frame.
Cold frame vs greenhouse…what is the difference between the two? The pros and cons of each?
Cold Frame Definition
A cold frame is a box made from wood with a plastic or glass lid on top. Plants are placed inside the box and the lid is opened or closed to allow air and heat to escape or stay inside the box. Although not as warm as a greenhouse, cold frames can keep frost away from plants.
A greenhouse is a building made from glass that is used to protect plants during the winter. Many, but not all, greenhouses provide supplemental heat which protects and nurtures tender plants during the cold winter months. In the summertime, ventilation, fans, and cloth or special paint may be needed to keep greenhouses from becoming too hot.
Cold Frame vs Greenhouse: Pros and Cons of Each
There are several pros and cons of each type of plant house.
Cold Frames – Pros
- Easy to make
- 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
- May be difficult to regulate temperature (too warm or too cold)
- Set on the ground so you will have to bend or crouch to work with your plants
- Small size makes them impractical for serious gardeners or large-scale gardens
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.
- 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 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.
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 be able to try this too.
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!
- Cold frames and hot beds
- Building and using hot frames and cold beds
- Season Extenders
- The Cold Frame Manual – with plans and instructions to build a cold frame – FREE
Jeanne Grunert is a certified Virginia Master Gardener and the author of several gardening books. Her garden articles, photographs, and interviews have been featured in The Herb Companion, Virginia Gardener, and Cultivate, the magazine of the National Farm Bureau. She is the founder of The Christian Herbalists group and a popular local lecturer on culinary herbs and herbs for health, raised bed gardening, and horticulture therapy.