I enjoyed your appearance on Permaculture Voices podcast. The thing about comfrey prefering some shade , especially in the afternoon, struck home with me. I received two miserable little bits of root last spring and planted them in separate beds, neither of which receive a lot of sun. The one in the sunnier bed faded away but the other, which had the shade of surrounding plants to shield it in the afternoon, survived and I was very happy to see it had returned from dormancy a few weeks ago.
