How to Build a Cold Frame

Every summer I look forward to fall when I can harvest the potatoes of my labour. And beets. And squash and tomatoes and carrots.

I also look forward to cleaning the garden up and putting it to bed. Let’s face it. We all have good intentions in the spring. We’re going to water every day and it will be fun and we’ll wear a sun bonnet and everything will look fresh and lively all summer long. We’ll deadhead all the flowers and it’ll only take a few seconds every day and we’ll keep things trimmed and THIS is the year the lawn will always be edged!

And then 2 weeks pass and we’re sick of watering, can’t be bothered to dead head, lose our sun bonnet and buy our second set of hanging baskets because the first ones withered and died already. Also the lawn looks kind of rustic with it’s long, hair edges so we’ll probably leave those as is.

With fall and winter come long days and nights indoors that aren’t spent scrubbing dirt out of our fingerprints.  It’s a rest from the outdoor work of gardening.

In keeping with my year of tragedy I’m going to keep the pain going.

I’m going to continue gardening alllll w i n t e r l o n g! Actually there’s no tragedy in that. Just a bit of work. But I’m excited for it.

Cold frames allow people in cooler climates to extend their growing season beyond the summer into fall, winter and even spring. Some crops actually grow throughout the winter, and others are just harvested then. The cold frame allows the plants to grow throughout the fall when they’d normally stop growing due to lack of heat and available sun making them ready for harvest in November and December.

There’s really no weeding involved and not much watering.  All you do is plant a few things this time of year (or a bit earlier) and then go out and pick what you need throughout the cold winter months.


I’m not gonna lie to you. I’ve never used cold frames before.

I felt inclined to work with cold frames some time early this summer so when I was driving down the road the other day and saw a huge selection of old windows and frames out by the curb I screeched to a halt, picked out 2 reasonable sized ones, threw them in the trunk, and continued on my way to my baton lessons.

If you can find yourself some old windows half your job is done.  Building the rest of the cold frame is a breeze, even for someone with limited carpentry skills.

The easiest way to build a cold frame is to simply build a bottomless box, that the glass window sits on.
The box should measure 12″ at the back and 8″ at the front in order to maximize the suns rays it catches.




If you can’t find an old glass window you can use plexiglass on top, or even thick clear plastic.  Glass is best, followed by plexiglass, followed by plastic sheeting.

Some windows from this era slid up and down on pulleys.  Because of this they have notches in the side of them. You can take advantage of those notches and build a slightly more advanced cold frame like this …


Cold Frame
Old Window For Cold Frame

Cold Frame Materials
Cold Frame With Rails
Glue And Clamp
When you initially cut your rails (I cut mine out of a piece of 1 x 4 with a circular saw) cut them slightly smaller than the width of the notches in the side of the frames. If the notches are 1/2″ then cut your side rails to 3/8″ or slightly smaller.
Cold Frame Build
Building Cold Frame 2
Building Cold Frame 3
Building Cold Frame 4
Building Cold Frame 5

Allow a bit of space between the back piece and the window frame, so it can slide easily over the back of the frame.  If it butts right up to the frame of the window it will hit the back piece when you slide the frame back. (see picture above)

Building Cold Frame 6
Cold Frame In Garden
Cold Frame In Garden 2
Cold Frame In Garden 4
There’s really nothing better about this cold frame than the more basic one.  It’s just fun to slide the window up and down on the rails. It’s based on the concept of something called Dutch Lights.  That’s what the glass on top of cold frames is called by the way; lights.

If you’re worried about the wood rotting over a period of many years where it touches the ground, you can set your cold frames on some 2x4s.  That way it’s the 2x4s that are sitting in the wet dirt, and they’re the things that will rot, not the cold frame you spent many, many laborious seconds building.

In a few days I’ll tell you what you can and can’t plant in cold frames and show you what I will be planting in them myself. If only I could find my winter sun bonnet. Otherwise known here in Canada as … a toque.



  1. theresa says:

    GREAT just what I needed to know and now need minions (what girl doesn’t) to knock out a few ’cause nothing is shorter than my planting season in Seattle!
    Breathlessly await plant list in your next dispatch.

  2. Sue Hontros says:

    baton lessons! Too funny. However, I wouldn’t put it past you. You probably have the big boots and shiny skirt already . . . or you’ll grow some.

  3. Did you know you could grow radicchio under the snow? No cold frame needed. My Italian parents Giorgio and Alda could tell you how to do it – they bring home beautiful red balls of radicchio all winter long from the cottage. And they figured out all this stuff without google, go figure.

  4. Nancy Blue Moon says:

    Great..I can’t wait to see what you grow during the winter!

  5. Jen says:

    Those are much nicer looking than my lazy cold frames. I put straw bales around the plants and place the old window on top. Farm-ghetto.

  6. Laura C says:

    Baton lessons?

  7. Mary Kay says:

    I have never heard of such a thing… and my grandparents especially my grandfather was a HUGE gardener. His garden was ONE ACRE! And yes I spent my summers there harvesting green beans. That was it just the green beans. We were not allowed to harvest anything else. But I spent lots of time at my grandmother’s side canning. So now I need to find a window – a cool window like yours. But will a new fangled window with double insulated glass work?? We have a cool salvage left over building supply store that has windows but they are of the newer kind.

    • Karen says:

      Hi Mary Kay – Any sort of glass will work. In fact your double insulated glass will work better to keep the heat in during the winter. ~ karen!

  8. Sandi says:

    Oh my God, Karen–you are amazing!

    ALSO. . . “rustic”. . . LOL. Yep, that word exactly describes my lawn as well right now. ;)

  9. Marti says:

    I feel like we’re learning so much about your talents this week. So far, that’s moonwalking, art (those diagrams with the tiny little plants are sorta “Primitive” style, aren’t they?) and baton twirling.
    It’s only Thursday… who knows what you’ll show us tomorrow, right?

    I actually thought, as cold as it gets in Canada, that the ground in winter there was sort of like “permafrost” and that anything planted in it would freeze solid. Are you putting those frames over things to prolong the growing season…or full on starting from scratch on growing new stuff?

    Also what do your neighbors think of this business in the front yard? Sorta reminds me of having a car up on cinder blocks…. or are you going to “share the wealth”?

  10. Theresa says:

    Have you not seen the fingernail tip on Pintrest? Before you go out to dig in the dirt, rub your fingernails along a bar of soap, that way the soap gets stuck under your nails, not the dirt. I haven’t tried it yet but it looks like a brilliant plan.

  11. Melissa Leach says:

    You never cease to amaze us.

  12. Ann says:

    I don’t have any cold frames, per se. But I have a way to cover many of my raised beds with differing row covers. Summer….Winter….Bugs…Chickens….are all pre problems here for me. So I have built wooden framed raised beds and eventually will have some kind of wooden trellis in each. And a way to cover them all. Because I garden more in the winter than in the summer. Last year I grew carrots, beets, kale, lettuce, winter rye(for the chickens to peck). This year I plan on growing more cool weather crops. I will add arugula, mustard greens(mostly for the rabbits), kholrabi, and I have even larger plantings of beets and carrots.

    If you can get these things started during the fall and have them mostly grown, they can stay in the cold frames to finish slowly growing thru the cold months. Or like the carrots and beets, they need to be pretty much done growing before the first freeze but are kept in the ground for storage purposes.

  13. Ev says:

    We’ve used cold frames only for starting plants in the spring. I look forward to a winter long tutorial on this! Thanks!

  14. Wendy says:

    We just built two double window frames for a school and I have to say… you’re is better! That would be easier for the little rug rats to move the window. We hinged these, since there are two windows. I think I may have to make a couple of single window versions… thanks!

  15. Emily says:

    Awesome tutorial… I love the pictures with text on them! I have never heard of a cold frame… until now. I love your blog… have I said that before? I am sure so and I am sure now I sound creepy! LOL

  16. Tigersmom says:

    Well, now I have heard of and know what a cold frame is. Not something you just grow up knowing about in Texas, I guess.

    Doesn’t mean I don’t still want one. Only in my case, it would be used to hide the plants I killed from all but anyone with a direct over head view.

    Stupid black thumbs.

  17. Mary says:

    This sounds like a fun project! Thanks for the tutorial!

  18. Rose says:

    If you use door hinges on the window. Then the frame can be a permanent part of the garden. The window can come off in the summer, then re-attached in the fall.

  19. arlene says:

    THanks for the reminder…. I was planning to modify one end of a raised veggie garden and give ‘er a go. I have an uncle who kept a tiny plastic covered greenhouse going all winter long (lives near Rochester) and grew spinach and the likes — my inspiration for southern ontario winter crops. Can’t wait to hear what you will serve up for us.


  20. dana says:

    AMANDA—-u could post on freecycle that u want a window or two. KAREN-QUESTION::: in the summertime could we just remove the glass/plexiglass “lights” & just use it like a regular raised bed except its not raised much? That wouldnt makw any difference if a few tomato plants or a teepee for pole beans was put in it. Just a thought because we have no storage either. LOVE YOUR BLOG!

    • Karen says:

      Dana – Yup, that’s fine! Just remember that you need time to plant in the cold frame. (if you want beets and carrots for your cold frame, you need to be able to plant in it by August). In that case you can plant beans early and when they’re done, you can empty the cold frame out until it’s time for carrots/beets. ~ karen!

  21. Annie says:

    And thank you!

  22. Annie says:

    I’m inspired!

  23. Becky says:

    Oh Karen, you wonderful talented woman. I want cold frames soooo bad, but I can’t talk my husband into it because we can’t figure out where to store them in summer, when everything would be cooked to death inside them if we leave them in the garden.
    Perhaps, i can show him your success with it, and that will bring him over to the dark side….wait, that’s wrong.. it’s probably the light side I’m bringing him over to. :D

    • Karen says:

      Becky – I have absolutely NO storage. So do what I do. Unscrew the frames and slide them behind the cedar hedge until the fall again. ~ karen!

      • Becky says:

        I’d have to plant a cedar hedge.. and my husband would flip. He has an irrational fear of cedar trees and such.

        I have thought about using hinges in the corners and making them foldable, but they’d be awfully heavy.

  24. Amanda says:

    OMG Karen, How did you know to post about how to build a cold frame? It is exactly what I needed and have been thinking about all week! I can’t wait to build a couple using your tutorial… I’ll send you pictures if its successful.

    Are you reading my thoughts? What am I thinking right now?

    Yes. You are right. Where to get an old window frame in my neck of the woods (NYC area)

    Thank you!

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