I noticed a couple of people concerned about the plants dying back in the fall. I bought a single plant several years ago at the spring garden fair. It has multiplied and we have a patch about 4 feet across. It dies back pretty much to the ground each fall. I leave the dead flowers stems through the winter as birds, particularly goldfinches, eat the seeds out of the heads. New plants also start from short runners at the edge of the patch. We dig many of these up and give away the starts so the patch doesn't get too big. Very easy to grow, they come back on their own every year.
I noticed a couple of people concerned about the plants dying back in the fall. I bought a single plant several years ago at the spring garden fair. It has multiplied and we have a patch about 4 feet across. It dies back pretty much to the ground each fall. I leave the dead flowers stems through the winter as birds, particularly goldfinches, eat the seeds out of the heads. New plants also start from short runners at the edge of the patch. We dig many of these up and give away the starts so the patch doesn't get too big. Very easy to grow, they come back on their own every year.