Hi, I presume you're asking about Clematis nellie moser, if so it's a group 2, early flowering 1, so cut back dead or damaged stems before growth starts in spring, then cut back any other shoots to strong buds, you should also get some flowers later in the summer, just dead head these, Derek.

Hi Snoop, the flowers you have had recently will be the second flush, just dead head these and leave the pruning till just before growth starts, then prune as above, the early flowers are on previous years growth, so after taking out any dead, diseased or damaged shoots, just cut back any other shoots to visible buds, these will provide the ramework for the following years flowers, whilst the stem that is left will flower next year, it is a bit complicated to explain, but Ihave tried my best, maybe someone else can explain it better, Derek.