Mine is seed grown from Geoscape Nursery. They offered 2 forms when I purchased, now the site has one. I do have paperwork down stairs. Mine survived the past 3? winters with no protection. I started with 2 and down to one now. Only minor tip dieback last winter with -13F. It's starting to get some size now which is good to see. It appears they need sun, sun, sun, sun. Keep that in mind. Mine gets 6hrs a day. The one which died gets 4-5 hrs a day, perhaps not enough.

http://www.geoscapenursery.com/Perennials.html