In article , Roger Van Loon
writes


Do others have experienced problems with the hardiness of C. montana,
anywhere in the UK?

As young plants I think they can be susceptible to hard frosts (but they
have to be hard), but as mature & young plants they can get a thing
called 'slime flux'. Some years ago we had a mild spell in March/April
and then some quite severe frosts in May. Lots of people lost their big
montana's - the RHS at Wisley was inundated with Wails! It seems the
sap had started to rise, then the frost had burst the stems - bit like a
water pipe I suppose. A creamy yellow slime oozes out of the stems at
the bottom and the plant dies, though if you prune it back below the
damage they often grow again. A small comfort though when your plant is
a beautiful 10 year old specimen.

This slime flux phenomenon is, I think, fairly unusual though, and
generally speaking I find montana's to be very amiable and perfectly
hardy, especially here in the UK. I have heard from Canadian gardeners
who have problems with it - but they have winters of horrid and lengthy
severity.

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.

Or is, perhaps, my C. montana 'grandiflora' a specially sensitive
clone?

I've always thought of grandiflora as being about the toughest of the
lot.

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