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How much builder's rubble is too much?
ashgrey100uxsN3HBt
Posts: 2
Hello there!
I'm building raised beds where there used to be a patio. Under the concrete slabs there's a fair bit of what I guess is builder's rubble: plenty of sand, and in places a seam of blue-grey powdery 'rock' that might be compacted cement powder? It's all very dense: before I went at it with a shovel, I wondered if some of the patio slabs had had a second layer of slabs beneath them! Beneath the rubble, it appears to be London clay, but even that is very compacted and in there I've found bits of plastic.
I'm planning to lay 12" of John Innes No. 3 above this, as I have plenty of mature plants in pots to put in. So my question is: should I remove everything I can? (It would be a lot of work, as it's a large raised be, but I'll do it if it's necessary!) Or perhaps I just need loosen it so that roots can grow through it? I'm hoping to plant a small tree in there, so ideally I'd want the roots to be able to go fairly far down.
Thanks in advance!
I'm building raised beds where there used to be a patio. Under the concrete slabs there's a fair bit of what I guess is builder's rubble: plenty of sand, and in places a seam of blue-grey powdery 'rock' that might be compacted cement powder? It's all very dense: before I went at it with a shovel, I wondered if some of the patio slabs had had a second layer of slabs beneath them! Beneath the rubble, it appears to be London clay, but even that is very compacted and in there I've found bits of plastic.
I'm planning to lay 12" of John Innes No. 3 above this, as I have plenty of mature plants in pots to put in. So my question is: should I remove everything I can? (It would be a lot of work, as it's a large raised be, but I'll do it if it's necessary!) Or perhaps I just need loosen it so that roots can grow through it? I'm hoping to plant a small tree in there, so ideally I'd want the roots to be able to go fairly far down.
Thanks in advance!
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