How to Build a Coldframe

Never ever underestimate the power of hoarding especially in the garden, it's what sheds were made for and if your shed is full it may be worth investing in another one. At Hopwood Kitchen Garden we have our eye on some corrugated plastic roof panels taken off an old building because they made the place too hot - sounds ideal for us - so a couple of students called Kirk Douglas and Gregory Peck are told to go and collect them*. We have over the last few weeks been collecting old roof trusses to build a coldframe. If you don't know how to build a coldframe, we'll show you how as part of our #autumngardening series. The final coldframe looks like this and is incredible easy to build. A coldframe is an incredibly useful thing to add to your garden and you don't have to spend a fortune to get one, they don't have to be pretty, they just have to be functional. Coldframes in spring and early summer are used to harden off tender young plants, such as half-hardy annuals and vegetables (you'll need this additional space as any greenhouse quickly fills up). At this time of year they are pressed into service again to overwinter young annuals and other plants that would keel over and die in the first frost. Also, if you don't have a greenhouse, they can be used to raise seedlings and grow them on into small plants.

gardening, make do, recycling

So, as part of our #autumngardening series we're going to show you how to make your own coldframe from things that may be knocking around your garden; you'll be surprised what can make a coldframe. Anything that will make a container will serve as a coldframe, in the past we have used tyres, old bricks, water bottles sunk into the ground, wine bottles sunk into the ground (they were fun to collect), packing crates and even loose bricks. Here we are using roof trusses or floor beams. Let's just say they're thick pieces of wood. For the top you can use old windows, old glass doors, glass taken from old UPVC windows (that's double glazing to you and me), thick plastic sheeting, corrugated or plain plastic.

how to build a coldframe

The students, Kirk, Gregory and WC Fields (a third year student overseeing it all) stack them two deep in a square shape. You can see this in the below photo.

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The joints at the corners are staggered, this gives some stability to the frame and if using bricks you would do the same. If you are using tyres you would literally stack them two high for larger plants or one high for small plants and then cover over with some plastic or glass. This has been very effective at Pig Row, we've even done this with an old coldframe were the glass has been broken.

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We then fill with plants to over winter, cover over with the plastic, it doesn't matter that the corrugated plastic is larger than the frame. You can then weigh down the plastic with some bricks to stop them being lifted off by the wind over winter. You would also do this with glass too.


In the end you have a simple but effective, cheap and upcycled coldframe using materials that we often throwaway. It will keep the plants snug inside and certainly after twenty-four hours you can see the difference between the plants still outside and those inside the coldframe. Try your hand this weekend at building one, doesn't matter how big, how small, just place it somewhere sheltered and keep checking it weekly over the winter period. Those plants inside will still need the occasional watering and you'll have to clear any snow off the top of it to allow light and heat in. Did we speak too soon about snow? Look what showed up just after we'd finished this job.

* please note for purposes of safeguarding all our students are named after deceased film stars. We never use their real names or show face on images of them.


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