Jeff Layman wrote:
"Eddy" wrote in message
...
[...]

Have done a brief google on this subject and found that "Rhododendron
ponticum" can spread.

Thanks.

Eddy.

Most of those big'n'blousy rhodos are hybrids that set little or no
viable seed. They won't spread. Even the true species (other than
ponticum) aren't particularly efficient at spreading by seed in a
short time.

See SRH's comments, authoritative as usual. I'll add my agreement about
R. ponticum's fairly modest rate of increase in any but the most ideal
conditions. Back in West Wales we had them along our little stream, on a
pretty neutral soil. I wish I'd taken notes, but I made a crude estimate
of the age of the oldest (about a hundred years), and, IIRC, deduced
that there may have been no more than about one or two surviving
seedlings per annum. The fields on either side had been stocked for all
that time, so I assume that poaching would have put paid to any
seedlings which tried to extend outward from the stream. An old group
near the house made a delightful den for the children, with the stream
running through.
[...]

--
Mike.