I put in 2 plants last spring...to use for herbal remedies and such...and the chickens ended up getting most if it...they're crazy for the stuff! This year we have bunnies too, and I'm starting new compost bins so that comfrey's gonna be working overtime I dunno about seeds either...I ordered plants. I rather doubt it'll spread much here either...I think it's pretty cold tolerant but it does like moisture and that we just don't have here in the high desert. Having to water seems a fair trade off for not having it take over though