I bought two pots that were about a two-gallon size with Echinacea Cheyenne Spirit (hardy to zone 4) in them last fall at Lowes. Left them out all winter on the south side of the house and they did come back. Not sure if your zone 6a would be the same as mine, but we had a somewhat mild winter here in southern Indiana.
I thought they were dead, so I planted petunias in the pots this spring. Then I noticed the echinacea starting to grow in the pots. As I saw the starts popping up, I transplanted them to a spot in the garden. They did very well then. I have a couple of pictures, but I am at work, so will have to wait to post them.
Coneflower (Echinacea 'Cheyenne Spirit')
