Hi folks,

I've built up very solid double brick retaining walls filled with
steel-reinforced waterproof concrete, behind which is a 30cm wide layer of
20mm scoria surrounding 2 parallel aggy pipes for drainage. The scoria is
wrapped with weedmat, and this is all to hold in some heavy-duty clay, which
is as tough as concrete in summer and like quicksand in winter. It might
sound like overengineering, but my workshop floor slab is 85cm higher than
the house slab, but less than 3m from it.

Between these walls and the surrounding fences, there is about 1 metre of
soil in which I've planted a whole heap of tropical plants, such as Cocos
Palms, tree ferns, Bouganvillea, Frangipanni amongst others.

My question is, if I want to create a rock and water garden between the
fence and the retaining wall (running parallel to both), would it be better
to concrete around the plants so that I can embed cobblestones, slate and
sandstone, or should I just lay down some very thick latex - cutting holes
for the plants - then cover this with screenings and just sit the rocks on
top?

My preference is to do the former, as I quite like the look. However, I've
been told that if I concrete around the plants, I'd never be able to dig
them up, but my feeling is that if I leave "enough" of a space around each
individual plant, I should be able to dig it up if it needs replacing. The
way I see it, if I have to dig up a plant because it's dying, then chopping
a rootball or hacking at a plant to remove it won't matter, and all I'll
need to do is replace the soil below it, and add more fertilisers, etc.

Any thoughts on the best way to get water running past these plants (with a
little trickle going into them as well)? The water that goes into the aggy
pipes will also be collected, filtered and pumped back up to the top again.

Thanking you in advance for any words of wisdom,

KC

www.twistedirony.com