If a montana is too big, what do you consider tall? 'Jackmanii' is a old and very much tried and true variety that gets about half the size of a montana with deep purple flowers produced in abundance over a pretty long season for a clematis. Considered an "easy grow" variety :-))

Jackmanii and other large flowered hybrids will need to be pruned each winter whereas the montanas do not. And fast growing is a bit relative with clems - ALL take about 3 years to establish properly before performing as described and most don't look their finest until after around 5 years. While these will need to be hard pruned each winter/early spring, once established they will rapidly regrow to their proper height.

Betty Corning?

I will probably get Jackmanii and going to look at Betty Corning. I have a few big flower types that do great, but they aren't as tall as I need I have some old fence wire wrapped on a tree with roses underneath. Just wanted one that would climb at least 10ft10ft. I just want something that others consider vigorous. AndAnd others are about 4 years oldold. Sorry for the crazy typing my phone is repeating words. Ugh.

Betty Corning is very vigorous for me. Last year it covered an 8' x 10' area with blooms until frost. Some say there is a light fragrance but I have not noted that with mine.