why does my clematis plants have very little flowers on

Question

there is an abundance of foliage but very little flowers

Answer 1

It could be too much fertilizer. There are other possibilities including lack of sunlight or improper pruning. These articles may help:
https://www.gardeningknowhow.com/ornamental/vines/clematis/getting-clematis-to-flower.htm

https://www.gardeningknowhow.com/ornamental/vines/clematis/pruning-clematis-vines.htm