In message , David in Normandy
writes
Frank Booth Snr wrote:

If you want to deter slugs from getting to your clematis, just
sprinkle plenty of sharp grit around the the base of the plant to form
a barrier. Slugs hate crawling over anything sharp or rough-edged.


I think this idea of deterring slugs and snails with grit or rough
edged stones / egg shells etc is over-rated. Either that or the little
critters here in France are mean and hard. S.A.S. Slugs. They have no
problems crossing ten feet of sharp granite chippings on my patio then
scaling a wooden table to reach some juicy seedlings in a seed tray.

I believed it worked until I looked up slugs in a gardening book, which
said they can slide along a piece of broken glass without injury. My
friend swears by crushed egg-shells and I tried it for a while. At
present, I am using Barnsdale Gardens organic slug pellets, which are
OK. However, I planted out some lettuce in a plastic bucket a few weeks
ago and thought I'd try one inch of vermiculite all around the edge of
the container on top of the compost. It seems to have worked. Perhaps
they don't like the dry texture of it or perhaps I have been lucky so
far. I have also tried using salt around the vents of a cloche and that
works extremely well until it rains.
..
I think slugs don't "hate" such things so much as mildly dislike them,
and may go around such obstacles - unless they sense something
desirable on the other side to reach.

One of my books advocates the use of garlic water, as recommended by a
lady who is a hosta expert but I haven't tried it yet. The downside of
that is it has to be re-sprayed after rain, during which the little
beggars will have had a field day.
--
June Hughes