How to Propagate blue comfrey?
Propagate by division in spring. Take root cuttings in early winter

blue comfrey · Symphytum × uplandicum
Also known as: Russian comfrey
Grow in moderately fertile, moist soil in sun or partial shade. Be aware the plant growth can be vigorous once established and has the potential to become a nuisance, so will require appropriate management. Can be grown for use as a plant fertiliser
Propagate by division in spring. Take root cuttings in early winter