I have had a Clematis Montana 'Warwickshire Rose' planted in a pot which for the last year or so has thrived, and produced abundant flowers through the summer. As we move into winter, the leaves on part of the plant are shrivelling and black, although the stems are still green when scraped back a little. I had assumed that the plant was simply losing its leaves in the winter, but I now realise that the other main stems are not showing this condition, and are retaining their leaves.
I have seen references to 'sudden clematis die-back' and am now wondering whether this is the cause.
It is on a south facing wall, southern UK, and has been fed regularly throughout the season. As a non-expert, any advice plse on this condition and action required would be appreciated.