In article , Nick Maclaren
writes
In article ,
Rachel Sullivan wrote:

Mary Toomey & Everett Leeds, in their excellent book on clematis reckon
montana's are hardy from zones 7 to 9 - that is not as tough as the
large flowered hybrids and viticellas that are hardy from zones 4
upwards. But it's still minus 17.7 to minus 12.3 C - which is still
pretty darned cold.

I assume that you mean USDA zones. Those are relevant in the USA,
and don't apply to the UK. There are lots of plants that are hardy
to zone 7 in the USA, and are tender in the UK (i.e. are hardy down to
only what would be zone 9b).

I know they don't apply to the UK but it gives a rough idea especially
as the OP was from Abroad. (Mary's book uses them in Europe as well.)

C. montana isn't one, though, and it is extremely unlikely that it
was killed by the frosts mentioned. I have not heard of "slime flux",
but some fungal or bacterial infection seems most likely.

Yes, I think so too. Slime flux is the only problem I've ever had with
montana's (that was caused initially by frost) and that's only coz I
deal with so many. I should think that most people never come across
it.

--
Rachel
Clematis Web Site
http://www.ukclematis.co.uk/