When we moved here 30 years ago, this plant was about 6 feet tall and flowered beautifully. It never looked like that again. Previous owners probably did something I couldn't duplicate.

After that it got much taller on very thin stalks, so when it flowered, the weight of the flowers bent the stalks all the way over so the flowers were on the ground.

Various incompetent pruning led to some years without flowers. But all new growth was always upward from the very top and the stalks never got thick enough to hold the weight of flowers. So either it didn't flower or it fell over.

After several years, I cut the entire plant off at the ground one fall. Pruning worked better after that. It never flowered at just 6 feet tall. But I did manage (not sure exactly how) to get it flowering every year and strong enough to stay upright and repeatedly bring it down to 8 or 9 feet tall (though it still has most of its growth upward from its highest tips).

I understand a naturally 15 foot tall plant is a problem for a spot that needs a 6 to 9 foot tall plant. But I don't want to start over, so I'll continue semi competent pruning.

Another observation is that it is very strangely deciduous. It stays green through very cold nights and snow storms in December and drops its leaves around Christmas. It seems strange that a plant that cold tolerant is deciduous rather than evergreen.