‘Nelly’ must be about the best known Clematis of them all, very frequently recommended. This one must have been here when we first came, but only appeared to us for the first time about four years ago. We had a dead tree which we had tried to get rid of with our then inadequate tools, and had to leave the trunk unfelled. Afterwards we came across these stunning clematis flowers which suddenly appeared all over it, and have been doing so ever since, with a little help.
C. ‘Nelly Moser’ is a Group 2 clematis so far as pruning is concerned, but there is a fair amount of variation in the pruning advice offered. Basically Group 2 Clematis flower in late spring/early summer on last year’s growth, and again in the autumn on the tips of the current season’s growth. (The later flowers tend to be paler). So there is a good case for not pruning at all, though the plant would need taking in hand after a few years of neglect. The best solution, I think, is to prune but only very lightly, in the early spring, before growth begins, by first removing dead or damaged stems, and then trimming all the remaining stems back to where there is a good pair of buds visible. From these pairs of buds should spring a framework of shoots from which side-shoots will grow and flower now. The later, younger side-shoots should produce the autumn flowers.