Hi Ravenclaw, first of all that isn’t syriaca, it’s tuberosa.

Second you really shouldn’t put it in a pot, they like the ground much better. It also helps with hardiness, not that that’s really an issue.

Last, it’s fall; it’s not dying, it’s just going dormant. Cut it off at ground level after it goes completely brown and I will come back up in the spring. Don’t give up on it if it doesn’t come up early. I had some that didn’t come up until mid June this year.