Nick Maclaren wrote:

In article ,
Roger Van Loon wrote:
I have been growing Clematis montana for some 20 years. (I'm on the
continent, near Antwerp).
It has generally done well and even seeded itself.
But I repeatedly lost some clones after a severe winter.
To be sure, last winter was not very mild - but other things, like
Fremontodendron, Ceanothus, Clematis armandii, and (would you believe
it?) Telopea truncata and Embothrium coccineum, came through unscathed
in my garden.
But - I once again lost Clematis montana 'grandiflora' (the only clone
I had growing at the moment): two plants, in different locations. (One
old plant had an almost 1 inch trunk). There was some green a week
ago, but now they have definitively given up.
Now - this species is rated as "quite hardy" by Bean, and "fully
hardy" by Christopher Grey-Wilson, and we all know that it gives a
spectacular show almost everywhere in the UK, every spring.
So my questions are -
Do others have experienced problems with the hardiness of C. montana,
anywhere in the UK?
Or is, perhaps, my C. montana 'grandiflora' a specially sensitive
clone?


I would bet ten to one that it isn't the frost that is the main
problem.
Almost certainly, you have some fungus or bacteria in your garden
to which C. montana is especially sensitive, and the frost merely
gives it a point of entry.

Here, last winter was definitely mild. Rarely below -5 Celsius,
and it never got down to -10 Celsius. Up to a decade back, and our
series of very warm, wet winters, that was unusual. We normally got
-10 Celsius at least once, and the ground often froze 2" down.

Regards,
Nick Maclaren,
University of Cambridge Computing Service,


Mmm - Yes, that's an idea, that might well be it. I hadn't thought of
that.
But then, it would have to be very selective: got some other species
and large-flowered Clematis hybrids, they don't seem to suffer. Is
there any mention in the literature of such a fungus or bacteria? And
have you ever heard of such a thing in the UK, attacking C. montana?
Over here, it was the worst winter in some 5 years. It did not go
below - 10 C in my garden, but there were repeated frost periods, some
rather long-lasting.
Thanks,
Roger.