Verbascum Chaixii 'Alba'

This white verbascum was planted in the herbaceous border at least 10 years ago and generously self seeds to increase my stock. I use it at the front of the white border, transferring seedlings at the appropriate time. For some reason, though, it loves to be in the pots I have around the garden for topiary box and really makes a nuisance of itself by blurring the clean lines I'm aiming for with the topiary. I constantly weed them out but, as you can see, it's very persistent. The plants in the borders finished flowering weeks ago and have been cut back but this one is as fresh as daisy!