I have 3 of these plants. One has grown rather alarmingly large and the other two are much smaller. The big one bloomed but the other 2 didn't. Maybe the freaky weather put the smaller ones off. If they do bloom, make sure you cut stems away before seeds are dropped. They like crevices, and are not so easy to extract as Bonariensis.

none of my large ones flowered this summer. I suspect it was the very cold winter.