My clematis vine is only flowering on the top, should I cut it back?
Certified GKH Gardening Expert
Make sure the feet are in the shade and the head is in the sun. Check moisture levels of soil.
Make sure they get a general feed in early spring.
Following the pruning information in the link below, you can clean up the vine at the appropriate time.
On a personal note, I had a summer blooming Clematis that was very sparse. I cut it to the ground and 2 years later a beautiful flush of flowers. A very hard prune may be an option for you.