Posted: 03/07/2016 at 11:36
If you want to cut it back hard, wait until late winter and cut it back to 30 to 90cm from the ground. Doing that every 3 or 4 years is an alternative way of pruning group 2 clematis. However, if there are any strong shoots you can cut back to just above those now.
I once cut 'The President' right back to the ground in later Winter and was rewarded by it sending up 11 shoots from below ground in the spring! Since then I've done this to quite a few large flowered early clematis to which I'd neglected pruning and nearly all of them responded in a similar way although I did lose one or two as I think slugs got the new shoots before I'd noticed them appearing.