Can anyone tell me the best way to prune an out of control clematis. I have one that seems to have suddenly doubled in size. I wanted it to cover an ugly fence but it is also growing out into the garden. I want to prune it back and get it under control but I don't know if I need to be aware of anything. I am sorry but I don't know the type of clematis. It has finished blooming now and the flowers have mostly died off. Any help would be appreciated.