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Brick/concrete raised beds, do they need lined?
pologirl
Posts: 3
Hi
as part of a kitchen extension building project with a raised patio, on a slight sloping garden, we asked our builder to build raised beds for us so we could enjoy the visual effect of planted borders from the raised patio. It will have glazed balustrade for safety & steps down to the garden. Our builder has built substantial double skinned raised beds with concrete blocks on the inner wall & brick on the outer. Our soil is clay and the base of the beds will be open to the soil. They are about a metre in width & vary in height from about 30cm up to a metre as the garden slopes. I wanted to ask, should I line the walls of the beds with a membrane of some kind? I was planning on a layer of hardcore/rubble at the base of them but what depth of topsoil/compost should I aim for?
I’m hoping these last for ever as we definitely won’t be doing a project like this again!
as part of a kitchen extension building project with a raised patio, on a slight sloping garden, we asked our builder to build raised beds for us so we could enjoy the visual effect of planted borders from the raised patio. It will have glazed balustrade for safety & steps down to the garden. Our builder has built substantial double skinned raised beds with concrete blocks on the inner wall & brick on the outer. Our soil is clay and the base of the beds will be open to the soil. They are about a metre in width & vary in height from about 30cm up to a metre as the garden slopes. I wanted to ask, should I line the walls of the beds with a membrane of some kind? I was planning on a layer of hardcore/rubble at the base of them but what depth of topsoil/compost should I aim for?
I’m hoping these last for ever as we definitely won’t be doing a project like this again!
I’d appreciate your advice. Thank you 🙏
0
Posts
They recommend lining sides with membrane and soil depth of 400mm
East facing, top of a hill clay-loam, cultivated for centuries (7 years by me). Birmingham
The depth of soil really depends on what you want to plant. If they're open to the ground, they can be quite shallow. Most plants will need no more than about a foot of decent soil - many won't even need that. Plants will just get their roots down into the ground if needed. All my raised timber beds vary in size, depth and height. Some are very shallow, especially the one I have an alipina clematis in.
If you want to put a layer of 'filler' in the deeper ones, I'd recommend putting a layer of landscape fabric or similar, over it, as the soil will work it's way down through it. Raised beds tend to settle and drop a bit anyway, so you'll find you'll need to top them up regularly too. Once you fill them initially, let them settle for a while before planting, frustrating though that might be! If you can add some rotted manure to your mix, that has benefits too. The big advantage is that you can tailor the soil medium to suit your planting.
It's worth doing a little lining, but there are waterproofing paints available too. Someone asked about this recently and I said I'd used Thompson's Water Seal on a house wall in a previous garden, when we'd built a deck from our house, which was raised, and we left an area at one end for planting. The timber sides forming the rest of the bed were plastic lined. House is still standing
I live in west central Scotland - not where that photo is...