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?
Regards,
Roger.

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,
New Museums Site, Pembroke Street, Cambridge CB2 3QH, England.
Email:
Tel.: +44 1223 334761 Fax: +44 1223 334679

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.

In article ,
Roger Van Loon wrote:

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.

Well, whatever-it-is that is called clematis wilt is pretty selective,
though usually C. montana is resistant and large flowered hybrids
aren't. No, I haven't heard of such a thing, but I have some fungi
that are almost equally selective in my garden (but with a completely
different range of species).

I am almost certain that there are a lot of undiscovered species of
fungi imperfecti and bacteria in the south east of the UK alone. If
they are parasitic on economically unimportant plants, are impossible
to classify without expensive laboratory tests, and have symptoms that
are similar to widespread diseases, they could remain unnoticed almost
indefinitely.


Regards,
Nick Maclaren,
University of Cambridge Computing Service,
New Museums Site, Pembroke Street, Cambridge CB2 3QH, England.
Email:
Tel.: +44 1223 334761 Fax: +44 1223 334679

The message
from Roger Van Loon contains these words:

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

No: I had one which happily survived -24C in Scotland (an exceptional
winter).

Janet

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/

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).

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.


Regards,
Nick Maclaren,
University of Cambridge Computing Service,
New Museums Site, Pembroke Street, Cambridge CB2 3QH, England.
Email:
Tel.: +44 1223 334761 Fax: +44 1223 334679

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/

Rachel Sullivan wrote:

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.

Thanks, Rachel. I had read about 'slime flux' (Mary Toomey's book, p.
89) but had not thought too much about it. But I now realise - that's
no too much different from Nick Mclaren's idea either, I think.
Anyhow, I did take a closer look at my plants (as I said, two of them
in different locations in my garden, many years old, one with a stem
of about one inch). The stems are now totally dead, down to the
ground. I don't see any sign of "creamy slime oozing from the stems" -
but that could have happened a few weeks ago, without my noticing.
Anyhow, this winter we had several cold spells, and the last one may
have been the cause, coming when the sap was already rising.
The thing that still puzzles me - it happened to my plants in the
past. And, thinking about it, I realise a few montanas in gardens
nearby have disappeared over the years. I know of others that were
growing nearby, and I will take a look how they have done this winter.
I know my garden is not that very much colder than Nick's (in
Cambridge), and I'm surprised that this plant can behave so
differently.
Regards,
Roger.

In article ,
Roger Van Loon wrote:

I know my garden is not that very much colder than Nick's (in
Cambridge), and I'm surprised that this plant can behave so
differently.

I was, once, but am no longer!

I have no end of trouble with something that kills germinating peas
and beans, but the ADJACENT garden doesn't. Weeble.


Regards,
Nick Maclaren,
University of Cambridge Computing Service,
New Museums Site, Pembroke Street, Cambridge CB2 3QH, England.
Email:
Tel.: +44 1223 334761 Fax: +44 1223 334679

"Rachel Sullivan" wrote in message
news
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
I have some great slides of it Nick!, bright orange slime (as the name
suggests) I have seen it on Montanas, C. grata, and suprisingly, late pruned
C. viticellas (although its not a big problem with the last as they regrow)
However I think Roger may have noticed the slime! so as you suggest some
sort of root rot is possible especially if it has been wet during winter.
But the burst pipe idea is quite true and I think it pays to hard prune
Montanas in June from time to time to avoid having one thick trunk.
Like Rachel I thought grandiflora was the toughest but I lost a ten year old
plant a couple of years back, not replaced as I reckon there are better
scented plants.

--
Charlie, gardening in Cornwall.
http://www.roselandhouse.co.uk
Holders of National Plant Collection of Clematis viticella (cvs)

Charlie Pridham wrote:

"Rachel Sullivan" wrote in message
news
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
I have some great slides of it Nick!, bright orange slime (as the name
suggests) I have seen it on Montanas, C. grata, and suprisingly, late pruned
C. viticellas (although its not a big problem with the last as they regrow)
However I think Roger may have noticed the slime! so as you suggest some
sort of root rot is possible especially if it has been wet during winter.
But the burst pipe idea is quite true and I think it pays to hard prune
Montanas in June from time to time to avoid having one thick trunk.
Like Rachel I thought grandiflora was the toughest but I lost a ten year old
plant a couple of years back, not replaced as I reckon there are better
scented plants.

--
Charlie, gardening in Cornwall.

Hi Charlie
"Bright orange slime", yes, I suppose I would have noticed that, if it
had been there. Unless it has a tendency to disappear totally in just
a few days.
So I'm left with the fact that two old plants with thick stems are
totally dead to the ground after the last freeze.
I had a talk with a local Clematis grower, yesterday. He is of the
opinion that Clematis montana, old plants especially, have a tendency
to die when there is a severe cold spell in spring, when the sap is
already rising. At least over here. He has not noticed that "orange
slime", but has seen many times old montanas die after a cold spring
freeze.
The amazing fact (to me) is that young plants seem unaffected. These
Clematis montanas of mine did seed themselves. And I just noticed two
of those seedlings, just a few cm. high, that are now producing leaves
- they did survive the winter perfectly well, in the same location,
totally unprotected.
And, thinking it over, I do not know of really old (thick-stemmed)
montana's nearby. Nothing like those that I saw in the UK. I suppose
something like "slime flux" must be especially active here.

Just another thing, Charlie. Remember the Ercilla volubilis that I
bought? It was just a yard away from one of the C. montanas, climbing
the same wall. And it has survived perfectly, just the tips are a bit
scorched. So, as far as I'm concerned, Ercilla seems hardier than C.
montana :-)

Regards,
Roger.

Just another thing, Charlie. Remember the Ercilla volubilis that I
bought? It was just a yard away from one of the C. montanas, climbing
the same wall. And it has survived perfectly, just the tips are a bit
scorched. So, as far as I'm concerned, Ercilla seems hardier than C.
montana :-)

Regards,
Roger.
Smelling wonderfull at the moment it is in full flower and untouched by
winter, Ercilla main claim to fame down here is its ability to withstand
salt laden gales, not many evergreen climbers can claim to!

[
I have a grandiflora alba which has spread over 50 ft in two directions with the usual magnificent dispaly every April , alas it now has only a hanfull of leaf shoots and looks pretty frost dead . Pretty sure its the long exposure to the deep frost we had that has done the damage . Still I'll leave it a little while to see what happens but I fear the worst .