In article ,
Emery Davis wrote:
On Fri, 29 Nov 2013 17:38:34 +0000, Sacha wrote:

I understand that but the OP isn't talking about a wall. He's talking
about it *between* paving stones, where many would grow low-growing
herbs if conditions were less moist or shady.

Well, I can understand getting the paving stones clean, especially if
it's nice stone, or slippery. But I agree, between the stones is another
matter. At Yamazakura, the Japanese house where I selected your Acer
ginalla -- which I hope is still alive BTW ! -- there is a lovely patio
with creeping thyme between the flags. As you walk on it in summer the
scent of the thyme rises up in the sun.

We have some wood fence with tons of lichen on it, I wondered the other
day if it's not making it rot a bit faster...

Acting as a sponge, you mean? All I can say - quoting Tresco again as
my source - is that there's a wooden fence on one part of the island
that surrounds a horse paddock. I've only known the island for 14 years
but to my certain knowledge that fence has been there at least that
long. Every plank of it is topped with lichen, so that it looks as if
it's rimed with frost, even in August. The fence should, in theory, be
destroyed if the lichen was harming it, or so I would imagine.

I hope you're right, that's certainly encouraging.

The main danger to a fence from lichen is that you will damage the
fence trying to remove it!

Overall, it is as likely to be protective as harmful, but both
effects are very small indeed.


Regards,
Nick Maclaren.