It is weedy and can get really leggy. It can be cut back and will produce a second flush but it is pitiful to see. By fall, it will be flat and sprawling. To top that all off, it self-seeds voraciously and the seedlings are splayed out and squat.
It is resilient. I will give it that. It will grow anywhere and stretch to reach the sun. In the nursery, it blooms as high as the delphinium. Of course, if I ever weeded the nursery, all thse blooms would come tumbling down!
I've yet to find the permanent spot where I can tolerate it but I keep moving it every year, still looking. This means that I now have Knautia everywhere