Comfrey is an herbaceous perennial that is hardy to USDA zones 3 to 9.
Comfrey is native to Europe and was introduced to North American when it was brought to this country by settlers for animal fodder. It now grows prolifically around the US and is a member of the boraginaceae family. It has large lance-shaped leaves that are deep green with pronounced veins; the stems and leaves of comfrey are rough and hairy and contain high water content. One of the most beautiful aspects of the plant is its vivid purple flowers that hang gracefully in arcs at the apex of the plant. These flowers bloom throughout the summer and are a favorite of pollinators, especially bumblebees.
Comfrey will grow well in many conditions. It thrives the best in moist, well-drained soil with high fertility and will grow in full sun or partial shade. It grows easily and vigorously, inviting some people to see it as invasive. Even after the plant is dug, ay remaining root sections will quickly propagate into brand new plants – making comfrey difficult to remove from its growing location. It’s best to choose a dedicated site and to allow comfrey to continue to grow in that location year after year.
Comfrey likes to grow and can be propagated by vegetative root divisions, which is the easiest method. Comfrey can also be grown from seed. Soaking seed in water for 24 hours before planting can help soften the seeds waxy sheath and allow the sprout to exit more easily.
Comfrey grows easily and is a great medicinal that can also be used as animal fodder and to enrich compost. On our farm, we feed the chickens comfrey leaves, as they are full of beneficial nutrients, minerals, and vitamins. Consider planting comfrey near animal pens, chicken coops, or pastures. Plant comfrey with eight inches between plants and twenty-eight inches between rows.
Comfrey roots and leaves have many medicinal uses. Containing high levels of allantoin, comfrey is a powerful cell proliferant internally and externally and is used to knit wounds and damaged tissue back together. Comfrey is a common ingredient in salves, poultices, oils, and ointments. When treating deep wounds care should be taken to avoid regenerating surface tissue before internal wound is healed and chances of infection are gone. Rich in vitamin B, amino acid, protein, calcium, potassium, and trace minerals, comfrey is a wonderful food source. Some people caution against using comfrey internally because of the presence of pyrrolizidine alkaloids, which have harmful side effects if consumed in large dosages, especially by those with liver disease.
This generous plant will give multiple leaf harvests in one season and abundant root harvests in the early spring and fall following two to three seasons of growth. To harvest leaves throughout the summer, cut the whole plant down to three to four inches above the crown and let it regenerate. Roots should be harvested in the spring or the fall when there is no aerial growth. The root grows up to two feet in depth and can be dug by hand. Remember, any remaining roots left in the ground will propagate brand new comfrey plants.
Post Harvest Drying Conditions
Pull leaves off the stems prior to drying to speed up the drying process. Leaves have a high water content and can easily bruise and turn brown Browning is caused by rough handling and by drying too rapidly in high heat. Comfrey leaf can also easily compost if not processed quickly after harvest. To process, lay out leaves in a single layer with minimal overlap. Good airflow is very important. Begin drying leaves with fans at lower temperatures of 80 to 90 degrees F. Then, gradually raise the temperature to no more than 100 degrees F after the leaves begin to lose some of their moisture.
Pests and Diseases
Comfrey has few pests and disease issues. Comfrey does naturally succumb to powdery mildew in the cool, autumn mornings towards the end of its growing season. Not harmful on its own, but powdery mildew can easily spread to neighboring plants and end their growing cycle more quickly if comfrey plants are not mulched.