Which is the best clematis to use?

Almost all of them are fast growing. You are more likely to have a problem finding a Clematis that is not fast growing. Clematis are water loving plants. The more water you give it, the faster it grows. Water every day for half an hour if you want maximum growth.

There are four flowering stages, you have to pick the one you want. Spring flowering means just that, it flowers in the spring and quits. Summer flowering means mid summer and quit, Fall flowering flowers in the fall. And lastly is Everblooming which starts in late spring and flowers until the first killing frost in the fall.

Also there are Evergreen Clematis that retains it foliage in the winter, but does not flower in the winter. Evergreen Clamtis generally have smaller flowers in the summer.

If your local garden shoppe does not carry a wide selection, order off the internet where there are plenty of all types and combinations of types available.

Also look up Montana Elizabeth although it has masses of pink/yellow centre flowers it is in bloom now, however it is a pretty fast one to cover a fence although will need some initial support.

Montana Rubens.