Slab planting problems

[Michael P]

I love forests and single trees on slabs, but have never had much success with this style. I've searched the forum, but can't find the information I need. There are two major problems:

1. My climate is very hot and dry in the summer (Dallas, Texas). The soil dries very quickly, is very hard to re-wet, and the trees remain water-stressed all the time.

2. The soil won't stay on the slab. It either falls off, or is washed off during thunderstorms or normal watering. I have tried making peat muck from native clay and sphagnum, but this cracks as it dries and falls off in chunks. Because the summers are so hot and dry, it is impossible to keep healthy moss in place to hold the soil. I have heard of using mesh to hold the soil, but what type works?

Thanks for any suggestions, and feel free to direct me to previous threads on the subject.

--Michael

 

[MichaelS]

I also live in a hot dry climate and these climates and stone slabs don't really mix well. But maybe the following can help.

* don't leave too much of the stone exposed to the sun as it heats up and dries the soil quickly. You still need to keep the trees in full sun so unless you have a misting system over head you will struggle to keep the temps of the soil down in summer if too much stone is exposed.

* make a ring of muck to hold the planting soil in place. You will need to find some kind of clay (akadama dust or similar) and mix it with peat and some long fibred sphagnum moss. Knead it and add water until you end up with a sticky putty like consistency and stick it the rock by pushing it onto a moist surface. You will need to allow for the water to escape from a couple of small gaps in the muck wall if the stone doesn't have drainage holes.

* The tree must be tied down with wire or something so it absolutely does not move. The final planting soil level should be raised around the nebari area so the level will end up lightly higher than the height of the wall. This give a nice natural finish.

* The inner sides of the muck wall should lean inward slightly and taper to a fairly pointed top so the soil mix will sit snuggly right up to the top without washing off when you water.

* You really must try to grow moss to hold everything in place. A good way to do this is to use some kind of finely chopped fibre mixed with lots of dried powdered moss and firmed well down on the soil mix. I find chopped coconut fibre is good. Fern fibre is better. If you can find some ferns that you can steel roots from and finely chop those, there's nothing better to get moss growing and to protect the soil surface while it establishes itself. Also cover the wall with powdered moss.

* While the moss establishes - about 3 months, keep a fine rosed watering can next to the planting and only used a gentle ''rain'' to water. Mist as often as you like.
Once the moss is fully established, even a thunderstorm will not bother the soil beneath. This may take 6 months.

 

[Michael P]

G'day mate, and thanks! Would potter's clay for ceramics work? And how about a very low growing sedum instead of moss? I can keep that alive over the summer.

 

[MichaelS]

G'day mate, and thanks! Would potter's clay for ceramics work? And how about a very low growing sedum instead of moss? I can keep that alive over the summer.

I missed the part about the muck cracking. Did you mix it 50/50 with peat? If it still cracks you are using a clay that shrinks. - no good. Some clays shrink as they dry and some don't. You can't mix peat moss with potters clay. You need clay dust of some kind. The sedums.....if you must but I still believe you can grow moss.

 

[Michael P]

Our native clay does have very high shrink-swell characteristics, so that may have been the problem. I do have some powered bentonite clay that is used for sealing ponds (among other things)--maybe that will work.

 

[Stickroot]

Seal the bottom and back of your slab with concrete sealer so moisture stays around longer.
Heavy clay mud mix for perimeter.
I put sifted peat moss in mine.
The "peat mud mix" starts to grow green moss in a few weeks and locks it together very well and looks natural.
I'll post some new pics, this is months ago.

 

[clevetromba]

I love forests and single trees on slabs, but have never had much success with this style. I've searched the forum, but can't find the information I need. There are two major problems:

1. My climate is very hot and dry in the summer (Dallas, Texas). The soil dries very quickly, is very hard to re-wet, and the trees remain water-stressed all the time.

--Michael

I've often wondered about this issue even here in Ohio. I had two willow trees up until this summer, and I couldn't keep them watered enough to stay really happy, and they were in deep pots, so the idea of keeping a shallow mound of soil on top of a rock moist all day just seems impossible.

 

[sorce]

If you can get moss growing well enough in early spring....

It oughta lock together well enough by the time it stalls in summer.

Put dog hair in your clay/muck.

Use a white tee over it.

Place smaller trees near the Slab to shade it.

Window screen will hide under moss.

Sorce

 

[M. Frary]

Use a pot.

 

[sorce]

And pot.

Sorce

 

[Michael P]

Dog hair! I have an inexhaustible supply sitting next to me as I write this. It reminds me of the horse hair plaster mix used early in the last century.

Thanks everyone for the suggestions. I will do some experiments over the winter, and use the most promising ones in potting season next spring.

 

[Cable]

View attachment 164791View attachment 164792 View attachment 164793

Dude that's frickin brilliant. I love rock planters but I never thought of layering flat rocks to build up a slab.

 

[Cadillactaste]

I've often wondered about this issue even here in Ohio. I had two willow trees up until this summer, and I couldn't keep them watered enough to stay really happy, and they were in deep pots, so the idea of keeping a shallow mound of soil on top of a rock moist all day just seems impossible.

Wonder if they could have benefited from a shallow tray of water under them...as I do my wisteria in summer.

 

[GrimLore]

Wonder if they could have benefited from a shallow tray of water under them...as I do my wisteria in summer.

No benefit. Never seen one on any that John G does. He always mentions to use moss on the muck and lots of water. As for his muck mix it really works nicely and I will quote his recipe here -

"Potters clay, Long fiber, and sphagnum moss...equal parts by volume....not weight...mix with water until you get a cookie dough consistency....keep it moist with a wet towel and its good for a season or more. I use a cheese grater to shred the clay so that it mixes well and I leave the LFSM long...don't chop it up. It has been mentioned several times in the videos...but most people never listen to the videos anyhow"

Grimmy

 

[Michael P]

Thanks for the recipe.

 

[sorce]

Thought of this thread when I wrapped my Lil feller in burlap right on the bench.

Reckon it'll stay there thru winter.

You got any pics?

Situation improving?

Sorce

 

[Michael P]

No photos yet. I am going to experiment with recipes over the winter, and use the best one when potting season starts next year. Definitely will try your dog hair suggestion.