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.