Planted this type clematis in a blooming condition last spring. During the summer it browned out over a two day period and died. In the fall I pulled it up it had no roots left. Any ideas why the root system failed?
As I posted on the other thread about the evergreen clematis, my guess is that either the plant got root rot from being kept too wet or an underground burying animal ate the roots. It could have been diseased with root rot when you got it and that is why it failed so fast when you planted it. I don't think that the evergreen clematis are prone to clematis wilt, but even if that is what happened to the plant, the plants normally recover from it.
I just don't find any of the cartmanii hybrids to be very robust plants. IME, they fail rather quickly and it is impossible to identify exactly why. I don't believe it is wilt, as neither of the parent plants are prone to this issue and the manner of decline doesn't match the wilt common to LFH's. I had one for about 4 years and removed it as it just didn't perform up to snuff. I do have a client with an Avalanche that has been in the ground for around 5 years. It's still alive but doesn't look great, is subject to significant foliar damage from winter cold and blooms very half-heartedly. If one desires an evergreen clematis and is in a suitably warm climate, I'd go with C. armandii before selecting one of the x cartmanii's.
I'm not impressed with my 'Avalanche'. I'm thinking the Arctic blast we had recently may have done it in completely and I'm not particularly sorry.
I removed my Avalanche after 4-5 years. It bloomed great and looked wonderful the first year, but then it got scale really badly and I cut it back. It came back, but very spindly and I got a few blooms. In the next few years, it just stayed spindly and hardly bloomed at all. I finally removed it this past summer.
I cut mine back hard the first two years but it is still spindly with few blooms. It did not branch where I cut it, just grew one vine. It has severe root weevil or earwig damage. Don't know which is the culprit but it disfigures pretty much every leaf. I wanted it because it is evergreen and I already have C. armandii 'Appleblossom' in another location and 'Avalanche' is smaller as well.
I would like to grow an evergreen flowering vine (not invasive) on a 20' trellis attached to a west facing brick wall. I've thought about cartmanii 'avalanche' or maybe c. armandii. Can't seem to find a mail order source for either of these. Any other ideas for a vine and a source would be greatly appreciated.
As far as I'm concerned 'Avalanche' is a dog, it is not robust at all. Mine did not bloom at all this year.
Based on my personal experience, I don't think any of the x cartmanii hybrids are particularly hardy plants and I'd avoid them in zones below 8 -- they are tough enough to grow well in a zone 8! And I'd have questions about how well even armandii would do in zone 7a -- it would be of marginal hardiness and likely experience considerable winter damage.
Evergreen vines that thrive in climates much below a full zone 8 are rare. And most that will thrive will be semi-evergreen at best. I might reconsider my options and go with something deciduous but fast growing, so coverage will be rapid and full, at least during the growing season. Perhaps a montana?