We moved into our house in July last year having viewed it spring when this amazing clematis was flowering all over the garage roof. Cut to this year - and so far worryingly little has happened to it. There are some feeble looking leaves and a few buds but it looks really unhealthy. it is massively overgrown - should we have pruned it in autumn? We are a bit clueless about these things. Am worried the dreadful winter has taken it off. Is there anything to be done? Tia.