These pictures illustrate nicely how large a PSB plant can get. This is not a crop to grow in a 12" container!
The mass of flowers is very attractive to bees and hoverflies, so they must be full of nectar. This is a time of year when there is not much food available for bees, so I strongly recommend you leave your PSB to flower if you possibly can.
Though not large, the flowers are individually very attractive too. Just think of them as giant Wallflowers (to which they are closely related).
Now it is time for the cycle to begin again. I will sow the seeds for next year's crop in the next few days.