[3759allen]

i'm going to make a raised bed over winter ready for next season. i've not had any dealings with raised beds and am after some advice.

i have just removed top soil from another part of the garden that i was going to use as part of the filling for the bed. some of this top soil is excellent soil, but some has a high content of pea shingle.

can i use this pea shingle/ soil mix in the raised bed? i was thinking as the bottom layer?

the raised bed is going to be quite deep so will be a decent layer of better top soil for the upper layers. the soil on the plot is quite well draining as it is so i'm concerned that the bed will drain too much. i'm guessing you can always water a bed but it's harder to remove the moisture / water logging. but i am keen on keeping watering to a minimum to save water and more importantly time.

any advice appreciated. thanks.

[Goosegirl]

To remove the shingle would be nigh impossible, but it should be ok as a bottom layer. Raised beds can dry out more than flat ones because using wooden sides allows the water to get through the wood, but you could always line it with some polythene? See what others think.

[mumofstig]

It'll be fine for the bottom layers 

[JayG]

Agree with the others - should be OK but would cause problems with root crops forking unless there was a minimum of about 9" of stone-free soil on top, although you would probably find the shingle slowly working its way to the surface anyway over time.

My soil is excessively free draining and I don't think a layer of soil+pea shingle could make that any worse than it already is. Yours may be more marginal - you could try loading it all into the bed, blasting it with a hose, and raking off the pea shingle to leave mostly soil (albeit rather muddy!)

[3759allen]

thats what i was hoping people would say.

i'm going to try ans sieve it all, the stone is so small it would be an absolute nightmare.

the beds will be quite tall to try and help my back a bit (i'm 6ft 3 so i have to bend further than most), so the bottom layer should be a long way away from the surface.

i'm actually making the beds from panels from an old commercial cold store, i acquired it to use the polystyrene for roof insulation in the garage and shed and have left overs to use up. i can't stand to throw things away (much to the annoyance of the mrs. lol) so i thought i would try and make a raised bed from it. it is 4 inch thick polystyrene sandwiched between 1mm mild steel. i know the metal will rust, but no more than wood would rot i think.

can anyone see any reason why i should use this? i'm hoping being insulated it will keep the soil at a more stable temperature, and with non of the materials being able to absorb water hopefully it won't suck moisture away from the soil. all theories i know but makes sense in my mind.