Cold Frame Greenhouse for a longer growing season

A Cold Frame Greenhouse: What you Need to Know to Extend Your Growing Season

Building a cold frame greenhouse to lengthen our growing season has been on our to-do list for a while.  In zone 5, we have trouble keeping fresh greens from the garden on our table for much of the year.  With a new shed, and an old window, we were re-inspired and put together a wooden cold frame for winter gardening.  Read below for information on building and using a cold frame greenhouse.

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How to Use a Cold Frame Greenhouse?

Depending on your climate, you may face challenges when trying to garden in the winter. Cold frame gardening is a great way to extend the growing season in a small space without a full sized greenhouse.

In general, a cold frame greenhouse can help change the climate inside your cold frame to a zone and a half further south.  This means if you are gardening in zone 5 you may be able to grow as if you are in zone 7.  This means you can only plant some crops that will make it through the entire winter if you are in zone 5. 

It’s also important to remember that getting too cold is only part of the problem in a cold frame, and on warm days you need to vent or open the window to keep it from overheating and cooking your plants.  While snow is a good insulator, heavy snow can break the glass and should be brushed off.  Just like more traditional garden, irrigating inside the cold frame is important since rain will not pass to the plants through the glass. You can hand water, but it is easy to forget to water.

In addition to fall plantings, cold frames can be used in the spring to give seeds a head start.  By starting your crops several weeks early in a cold frame, you can either transplant them to the real garden when the time is right, or simply remove the window.  This can help your garden get going a whopping 4-6 weeks earlier start than plants put directly outside.

What to Grow in a Cold Frame Greenhouse

The best crops to grow in a cold frame greenhouse are plants that can handle fluctuations in temperature and even temperatures below freezing. Salad greens are excellent choices such as spinach, chard, lettuce and arugula.

You can also plant cold loving veggies like onions, carrots, radishes, brocolli, and brussel sprouts.

If you are starting seeds or using the cold frame to harden off certain vegetables, pay attention to your daytime high temperatures and make sure to vent your cold frame.

Building a Cold Frame Greenhouse

Build your cold frame with cedar boards and make sure to avoid pressure treated woods.  Our cold frame is moveable, but for now we placed the frame right across the front of the chick coop and goat shed, and will hopefully add a bit of warmth to the shed in the winter time.  With our new frame built, set up and filled with dirt, we’ve started with a few transplanted lettuce plants. Since the box is small, I’m going to focus primarily on salad greens.  The key is to plant these greens early enough to get a head start before shorter days and cold temp slow their growth. 

Other Options Besides Building a Cold Frame

There are several other options besides a cold frame for extending the growing season including row covers, hoop houses, and greenhouses. Instead of building your own cold frame, you can also purchase a cold frame greenhouse directly online or at your local gardening center. A cold frame greenhouse is also a great addition if you have limited space as it can be added to a porch or patio

 
 
 

Greenhouse Cold Frame

Clear Cold Frame

Row Cover

Mini Portable Greenhouse

6 thoughts on “A Cold Frame Greenhouse: What you Need to Know to Extend Your Growing Season”

  1. Good for you! I have made cold frames from bales of straw and an old window before and kept lettuce until after Christmas in them. This year I never got my act together early enough to grow anything in a cold frame 🙁

  2. I have a cold frame and started lettuce and spinach in it in late August early September. The seeds sprouted and formed one set of leaves but with the shortening of days they have quit growing. They are just sitting there. I am going to have to try a grow lite I guess. I am disappointed. I really need a small green house.

  3. Nice cold frame! I added one outside my greenhouse for hardier plants with a leftover window from a remodel at our house. The real benefit was that it still had the screen. So in the summer I can open the window and use it to harden off plants b/c the screen keeps the free range hens from eating the plants. Which is what they did the first time I put beautiful new transplants outside the greenhouse to harden off!! Stevie @ruffledfeathersandspilledmilk.com

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