Slab Planting Questions

Thaddeusjd

I am hoping to do a slab planting later this spring, once it warms up a bit more. I do have some questions, having never done a slab planting before. It is going to be a planting of dwarf bamboo.

1) I have three chocies of slabs sitting in the basement. One each of limestone, sandstone and slate/shale. (I thinks its slate, I have not seen shale that large before, but I might be wrong. I am leaning twords the sandstone, and away from the limestone. I am afraid of the limestone leaching lime into the soil. Would sandstone be a good choice here?

2) Can anyone give advice on how to make the muck to build the outer wall with? I have seen a few recipes, some involving potters clay, some advising the use of human or animal hair in the mix.... Does anyone have a mix that has worked for them in the past?

3) Moss. I plan on using moss as an accent, how much of hte surface should the moss be allowed to cover? I know if there is too much, the top layer becomes like an umbrella and no water reaches the soil.

Thanks!

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Attila

Hi Thaddeus

The most important point with the slab is to resist the moist conditions without cracking. Other than that, all the choices you mentioned are fine. I only have a little concern with the sandstone: it is the most prone to weathering and deteriorating if kept wet all the time. So, make sure that it is very hard and solid.

As far as the lime leaching into the soil, that's not the case. The frequent watering will wash out any lime from the soil (I still have my childhood memories growing up in the Carpathian mountains with its rugged limestone peaks covered with lush green alpine vegetation). The only plants not to be planted on limestone are the ones thriving on acid soils, such as azaleas, camelias, stewartias, heathers.

For muck (careful for spelling) I used a mix of heavy soil (containing enough clay to make it sticky), fine peat moss and some sphagnum moss (2:2:1). The clay makes it stick, the fine peat moss holds moisture and is good for growing moss on the muck, the sphagnum moss adds fiber for holding it together. You can add potters clay to the mix if the clay-content is too low. I haven't used hair but I am sure it works well.
The focus here is not to let it completely dry out. When that happens, it can crack and it repels water.

On bamboo planting you can let the moss cover the entire surface. It will actually look very good that way. Your worry that the moss acts like an umbrella and no water reaches the soil is entirely groundless. In fact, the opposite is true: moss keeps the soil moist all the time. In most cases you have to keep a portion of the surface without moss in order to prevent the soil from becoming too wet. However, this is not the case with your bamboo planting, which loves moist soil (good drainage is still important, though). The only moss that can prevent the water from entering the soil is a very thick and companct layer of bone-dry (=dead) moss.

Regards,
Attila

Treebeard

Hello Thaddeus,

Attila has it pretty much covered really. There are a few things I would add though:

1. Whichever base you use, drill a couple or three holes in it. This will help you to tie or wire the bamboo onto the slab should it need it. The holes also serve as drainage holes. My personal preference would be for the slate.

2. For muck, I use a little modelling clay mixed with peat. The two need to be really well mixed. If you break off a lump, it should to stay bound together and not crumble apart. The clay is the sort that cures in the oven and doesn't need high firing. NOT the coloured primo or prima or fimo or fima or whatever it is called.

3. It is a good idea to fix the moss in place with wire staples. Just bend some off-cuts into a U shape and press them in. It really does help the moss to establish, at least in my experience. Finally, it cannot be stressed enough - Don't let the planting dry out! As Atilla says, once it dries out it is very hard to wet it again.

Good luck with it, remember to take some pictures!

Regards,

TB

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D3rutat

If you are still afraid that the moss might prevent correct soil watering you can use the immersion watering method. Here's a link from Colin Lewis whith good tips on slabs:


http://www.btinternet.com/~colinlew...ing/Cement.html

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