How to Build a Cold Frame

Winter Garden and Cold FramesShould you choose to have a cold frame in your garden, you’ll hopefully find the following tips and advice on how to build a cold frame useful. Having a cold frame is very useful for growing ornamental plants and vegetables from seed, not to mention growing cuttings or protecting anything that’s not a hardy plant from the excesses of winter. Building your own cold frame is one of those jobs that any DIY home enthusiast can accomplish and look back on with pride.


Depending on whereabouts in your garden the cold frame is to be located you could use a variety of materials to build it with. Traditionally, a cold frame has a timber frame with glass windows in its top, which is a hinged or sliding lid. If the cold frame is to be located out of view from the area of the garden you use for relaxing in, then there’s no reason at all why you can’t just use scraps of old timber that are lying around your workshop and something like an old glazed door or window frame for the lid.

However, bearing in mind that your cold frame needs to be located in a warm sunny spot in your garden, it may well end up being visible to any visitors in your garden. So, bearing that in mind here’s one idea for how to build a cold frame - that will look good anywhere in the garden. NB. The timber you use needs to be either pressure treated for outdoor use or, treated with a weatherproof paint or stain before starting work on the cold frame. For the walls of the cold frame, treated floor boards are ideal.

The Size and Shape

Cold frames usually conform to one of two designs, either an apex top on gabled ends or a pent top, which in some parts is known as a skillion. Creating a pent top is easiest as being just one surface it can be hinged to, slide across or even just rest on top of the frame. However, for this design we’ll use an apex top on gabled ends.

Whilst a cold frame is normally only 18 inches high you can make it as wide and long as you wish, so some of the dimensions here are merely guidelines that you can play about with according to the space you have available in your garden.

Building the Cold Frame

Cold FramesUsing four pieces of 2x2 as corners fix 2 of the treated floor boards to create two side and end walls. The end walls need to be gabled.

On one of the ends fix two pieces of 1x1, side by side and one inch apart, inside what will be cold frame and at the center of the end, so that they are 18 inches high from the floor upwards.

On this end, above the two existing floor boards add to more that are cut to create a triangle shape finishing the gable end. Repeat this for the other gable end.

Create fascias and barge boards for the sides and gable ends from 2x½ inch timber.

Make a ridge bar from some 3x1 and slot it in between the 1x1 posts at the gable ends. Onto the ridge board you can fix the tops with hinges. Whilst you could construct a glazed top yourself from timber, it’ll save a lot of time if you buy a couple of suitable window frames and fit those instead. For a cold frame roughly 3 foot by 4 foot, window frames with eight small glazed units would be ideal for each side.

Photos by Linda N and greengardenvienna, Creative Commons License