I have two Clematis in my garden, one is at least 7 years old, and the other is 2 years old. The older plant produces good blooms but from the ground level up for about 14 inches there are no leaves, blooms, etc just bare stems.

The other plant (the 2 year old one) has good leaf and bloom coverage from the ground up to half way the height of the plant, then it's just bare vines then the top half is full, good leaf coverage and blooms.

What can I do to encourage new growth in the bare spots of the two plants?

My neighbor has an older Clematis that has leaves and blooms from the ground up to the top every year and is just beautiful. Again how can I get this kind of coverage on my two plants? Unfortunately I don't know the variety of Clematis I have.