Comfrey is adaptable to many soils, but prefers moist, fertile soils. Thin soils over rock will give a poor crop, but on light sands and loams, this crop will be productive if adequate nutrients are present. Comfrey is propagated from root cuttings, crown divisions, and transplants. Production during the first year is greatest for a crop started from transplants and lowest for one using root cuttings. After the first year, comfrey yields the same regardless of propagation method.
Root cuttings are the least expensive method of propagation, and consequently, are used most often.
Smaller cuttings will also generate plants, but plants from longer cuttings emerge and establish more quickly. Wilted cuttings should be soaked in cold water until they become firm before planting. Root cuttings develop buds about 3 to 6 weeks after planting, while crown divisions emerge in about 10 days. Prickly comfrey is propagated by seed in the Soviet Union. Till the soil so that it is free of perennial and annual weeds, and is level prior to planting.