Comfrey: The Garden’s Swiss Army Knife

Comfrey in shady site in my garden

Recently I have been exploring “natural ways” in which to help the garden, especially the vegetables that I grow every summer. At risk for pests and diseases, tomatoes, peppers, and cucumbers need all the help they can get. I have always heard how comfrey is used in permaculture so last year I purchased two plants of Bocking 14 (Symphytum x uplandicum). Hardy to zone 4, this herbaceous perennial is a hybrid of S. asperum and S. officinale.

I put one plant in a shady, moist area and one in a sunny, dry location. This summer, the one in the shady, moist area is much larger, about 2 feet tall and wide. The plants have large green leaves, up to a foot long, arising from a central crown. The foliage is bristly, making gloves necessary. The other one in the sun is not doing well. In fact during a long dry spell I had to hand water it and I am not sure it is going to make it.

Comfrey has many uses: pollinator/beneficial insect plant, medicinal herb, animal feed, fertilizer, compost green, and mulch. The plant blooms small, bell-shaped blue flowers that fade to pink. The shape of the inflorescence reminds me of fiddlehead ferns. It starts flowering in the beginning of summer and can continue in the fall. Because it is sterile, Bocking 14 will flower and produce nectar and pollen but not viable seed. The flowers attract predatory wasps, lacewings, and bees.

Comfrey Flowers, Organic Vegetable Garden, Potomac Overlook Regional Park, VA

As a medicinal herb, the leaves are a source of a cell-proliferating molecule called allantoin which is needed for the healing process. Also known as “knitbone,” comfrey leaves can be used to create a poultice for bruises, inflammations, swellings, cuts, and burns. The leaves can be dried to make a powder, used to make a salve, or infused to make an external tea. This plant should not be taken orally.

Comfrey is commonly used in permaculture as a companion plant to fruit trees. It is used as a living mulch and a weed suppressor. It is also used as feed for pigs and poultry.

One of its claims to fame is that its deep roots bring up nutrients from the subsoil, re-locating them throughout the plant. Comfrey has potassium, phosphorus, calcium, copper, iron, and magnesium. Because it is an excellent source of potassium (the letter “K” in NPK), it is very beneficial to tomato, pepper, and cucumber plants. By cutting the leaves and placing them under another plant, nutrients are brought to that plant. After harvesting leaves, the crown sends up new foliage quickly so the plant can be harvested 3 to 5 times per growing season. Alternatively, a nutrient rich compost tea can be made with leaves and water.  Comfrey also can be added to compost piles as the “green.” It breaks down quickly and helps to activate the compost pile.

There are so many uses for comfrey that I am looking forward to experimenting in my garden.

Comfrey at Ladew Topiary Gardens in MD