I have a climbing Clematis Montana (Gothenburg) which I planted in May (I'm in East England). As this is a group 1 variety, it is supposed to flower early — I haven't seen any flowering this year. It climbs very vigorously, and has already reached ~3m height. I read that Group 1 Clematis is supposed to be pruned after flowering, and that the harder (unpruned) branches are more likely to flower the next year. The leaves have now started to wilt (see picture at the bottom). The aim is to get a more even/denser covering of the trellis next year.
Should I prune it and/or prepare for the winter in any other way?