#1 There are varieties of comfrey that are sterile, and spread only by root cuttings (bokking #14 and 44) and there are varieties spread by seed. 98%of gardeners want the sterile variety. Perma Pastures had a fantastic vlog on how large of a root piece was required to propagate…..only an inch or two, and it will be coming back next season where you planted it. I was surprised the segments were so small. Some people just rototill the comfrey bed when they want it to spread.
#2Plant comfrey where you will WANT it. (It will never leave, because it has an 8-12 ft. tap root.) Kinda like grandpa’s horseradish.
I chop and drop the entire stem and lay it at the base of my rhubarb. The parts I chopped grew back to 3/4 the size of the unchopped stalks in two weeks. So fast! Multiple harvests per season are possible. Fresh leaves degrade quickly without any bad odor. Stalks take longer to break down, but the rhubarb doesn’t mind.
When I put it in water for the ducks, it turns a pretty atrocious color of brown quickly…by the end of the day, but probably makes a lovely plant food tea. I have put it in my anaerobic weed tea fertilizer before (David the Good’s fetid swamp water fertilizer)
Chickens ducks and quail ALL love the leaves and decimate them when put into cages or enclosures. Quail have tiny beaks, so the stalks tend to go in the compost bin. It has a good protein content….I think about 14%, and an excellent supplemental livestock food source.
It can be chopped and hung to dry for feeding in the off-season. I want it so badly to be frost tolerant, but it’s just not in zone 6a/6b.
I have dug up roots from the original plant, and have one plant at each fruit tree in the orchard. I was told that comfrey is a “mineral miner” because its tap root draws nutrients from deep in the soil and is a good companion plant for fruit trees. My orchard has atrocious clay, and I basically made “hugel holes” for my fruit trees. 3′ x 3′ hole with logs in the bottom, twigs, straw/grass and then soil. The comfrey is part of the long game in improving the soil.