I'll have to keep an eye out for that one, Greg. I'm going to bet it's plenty Northern hardy, as Dr Griesbach I think was out of University of Chicago, and Klehm grew plants in Wisconsin.
Name: April Blevins North Eastern Kentucky (Zone 6b)
I love everything about this thread. Purples are my favorite and I got several ideas of plants I need from the pictures, so thanks everyone for sharing.
I'm in the South, but I want to share my pictures of Paul Voth, mentioned earlier in the thread. It's a tall tetraploid that blooms late. Unfortunately, mine got rust, but I imagine in the North that wouldn't be a problem.