Prickly comfrey has pink and blue flowers while Quaker comfrey has blue, purple, or red-purple flowers. Seed production is rare, and crops are usually established from root cuttings and crown divisions. Vegetative growth does not cease with the start of flowering, and the plant will add new stems continuously during the growing season. The plant will grow rapidly after harvest and flower again. Comfrey crowns and roots are very winterhardy in northern Midwestern environments.
Comfrey produces the highest yields in full sunlight and under cooler conditions.
Unlike annual crops, the leaves do not readily wilt during extended periods of drought due to its deep root system. This crop is also very frost resistant. 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.