Did you inherit a clematis and have no idea if it’s a Type I, 2 or 3 aka A, B or C? Or are you just not sure, in general, how to prune your vine? Here is some great, very simple advice from Minter Country Garden:
"Looking for a simple method to follow for clematis?
• For clematis that bloom in late summer, cut them back now by about 75% or to about 1-2’ above the ground.
• For clematis that bloom twice in a season, cut them back by about 33%.
• For clematis that bloom before June, leave them be, otherwise you’ll be cutting off this season’s flowers (typically they need little pruning, but if you need to trim it, do it after the vine finishes blooming)."