I have heard of them being planted in a sunken bucket, but I would not put it past it to get out via the drainage holes. We were replanting a very long herbatious border in a ladies garden, she had put a couple in the back of the border and two plants had spread 75 metres. I was using a digger to get down far enough to get the roots out and even now after 10/12 years of trying to eradicate it she still sees it pop back up, and of course it looks so striking she leaves it to flower, then digs it out with the winter maintenance. By then it has thrown out a few more suckers which get missed and up they come again. Even painting individual plants with brushwood killer has not worked.
I think it is a bit like lilac, if you prune it, then it will start suckering even more and as you have to cut it back at the end of each season it's a vicious circle.