I have a few Barbara Karst Bougies growing on trellises, and they are rather spindley. There's a lot of nice, green bushy new growth at the bottom that's starting to get color, and a lot of bright color and long shoots at the top.

The problem is that there's a solid 2-3 foot section in the middle with almost no branches or leaves. How do I encourage growth there?

Right now, they're about 7 feet tall. The bushy section at the bottom goes about 2 feet up. Should I cut them back all the way down to this new growth in the fall to encourage healthier plants next spring?

They came with our house, so I have no idea how old they were, if that has any bearing...

Thanks for any and all help!

-Vicki