The genus Clematis is usually split into three groups, based on the time of year that flowering takes place as a result this web site has a separate entry for pruning each group.
The pruning of the particular species is dependent on which group they're in. The different groupings and species require pruning in particular ways, so there is a note of caution: if you're not certain what kind of clematis you have then we won't prune! We'll wait until they've flowered! There are so many different varieties that's it's best left until flowering, rather than guessing, even when that guessing is based on pretty good knowledge!
Group two Clematis
The group includes and C. 'Niobe', and those with double or semi-double flowers, including C.'Vyvyan Pennel'.
We'll prune these in the late winter by making sure we remove the dead and dying stems and we prune back to just above a strong pair of buds. We'll also make sure that the new stems, both old and new, are well supported so that in turn it supports the heavy flowers.
Group two clematis includes Star on India and C. 'Nelly Moser' (above)
The aftercare of Clematis
During our on-going pruning of clematis we’ll ensure that any new growth is supported either by whatever is to hand (tree, downspout, trellis etc) or by a stake. We’ll also give the plant a good feed with fertiliser after pruning and ensure that there’s a good mulch spread around the base of the plant.