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Recomendations please!
Flower Girl3
Posts: 111
Hi All,
I am planning this year to knock down an old shed and put some raised beds in instead, it has concrete underneath it and would be impossible to dig up so any ideas on what sort of wood I would use to make my raised beds and also what to hold the soil in with to stop it escaping from the bottom! All help appreciated and advice would be great thank you!! 
0
Posts
I don't think you can make beds without any drainage. Essentially what you will end up with is like a pot without drainage holes.
You will need to find some way of breaking up the concrete base.
When you don't even know who's in the team
S.Yorkshire/Derbyshire border
Maybe you could be able to put a second base in it, raised above the concrete with drainage in that base?
The thicker the wood the better and sleepers will last the longest. However, timber decking boards are treated, good value and will last a decade or more. Most of my raised beds are on soil but when I've had to build on concrete I used woven landscape fabric, stapled to the inside with galvanised staples to prevent soil running out of the bottom. You'll need to make them deeper than when on soil and it's advisable to put down a layer of gravel etc to help drainage (put that down and lay the landscape fabric on top of it then fill with growing medium.) I used bought-in topsoil mixed with well rotted farmyard manure. In my early attempts, I filled them with bagged multi-purpose compost but found it degraded and plants stopped growing well after a few years, hence the switch to the topsoil/manure mixture which only needs top dressing with more FYM every couple of years or so to stay fertile.
BobTheGardener I was thinking of landscaping fabric so it can let water out, and I have been using potato bags for a couple of years but I want something more permanent now!!