Douglas Alpenstock wrote:
I wish that were true here. I go to great lengths to harvest seed. I wonder, at what stage could I harvest the roots and bring them into my cold room to jumpstart next year's production? This would be huge.
Douglas, our winters are much milder than yours so we leave them in ground, I have never lifted them. Perhaps you could try leave some plants in ground and protect with a heavy mulch and removable cold frame?
I would guess that if you wait until the leaves have all started to die back in autumn that would be a good time to lift them.
Please do let us know whether either or both methods work for you.