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Cold Frame on a garage roof

Hi all,

I'm thinking of making a cold frame to sit on the garage roof, which I can use to get seeds started.

Why the roof? well it gets plenty of sunshine. I could stand on a raised planter behind the garage and comfortably reach into a cold frame, and it doesn't entrude on an already fairly small garden.

It's a flat roof made up of GRP over timber by the way.

Can you see any issue with doing this?

I did wonder about the roof being cold, maybe sitting the seed trays on polystyrene sheet would help? To insulate them a little.

I've never planted seed trays or used a cold frame before either image.


  • FireFire LondonPosts: 6,724

    I would just wonder if you could comfortably get a hose or watering can up there to water the frame. And lift the frame fully to do it. Maybe put a support under the cold frame to protect the roof a little.

  • Yeah the waterbutt would be right next to me. Lifting the roof high enough is a good point, I'd have to come up with a prop idea to help lift and keep the roof help up for me.

  • FireFire LondonPosts: 6,724

    I would say, from experience, that any system has to be dead easy to be sustainable - no big stretches or special odd equipment. To me anything that becomes too much of a faff ends up sliding. Not to say your system might not work. Just make it easy as poss.

  • KT53KT53 Posts: 4,268

    You seem to have access to it sorted so my main concern would be how it could be affected in high winds.  How do you plan to keep it in place.  A normal cold frame isn't anything like as exposed and can be pegged to the ground in windy locations.

  • hogweedhogweed Central ScotlandPosts: 3,990

    I'm not sure there are many new coldframes these days with glass in them, they are mostly polycarbonate so very light. You would need to fix it in some way on to the roof and keep it closed on windy days. Why not give it a go this year and see how you get on. If it doesn't work you can easily relocate it into the garden. 

    'Optimism is the faith that leads to achievement' - Helen Keller
  • Good point with the winds. I will have a think about weighting the thing down internally so it doesn't blow away. Maybe an internal floor which allows the water to flow out but would allow bricks to sit around the edges as ballast..

    I was planning on making this myself out of timber and a plastic roof. But need to look at that in more detail yet. As yet I haven't seen any cold frames I could buy which are suitable, though they are very close.

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