Common Comfrey: Plant Care And Characteristics

How To Grow Comfrey Or Symphytum Officinale

Comfrey, or symphytum officinale is a clump-forming perennial herb prized for its pollinator-friendly features, showy flowers, essential nutrients made available in compost or liquid fertilizer, and easy maintenance. Learn how to grow and care for comfrey. 

Quick Facts:

Botanical name Symphytum officinale

Height 1 to 3 feet (.30 to 1 meter)

Spread .75 to 2.5 feet (.23 to .76 meters)

Sun exposure Part to full sun

Soil requirements Adaptable to most soils but prefers a moist but well-drained, fertile soil with a pH of  6.0 to 7.0

Hardiness zones 4 to 8 

When to plant Spring

Comfrey plant is a perennial herb your grandmother probably grew and maybe even your great-grandmother. It’s a time-tested plant that requires little maintenance once it’s established and is at home in any garden. Comfrey boasts showy flowers and is often included in pollinator gardens. It can increase soil fertility when applied as a liquid fertilizer or allowed to compost. 

Comfrey originated in Europe and western Asia and arrived in America during the 1600s for its medicinal qualities. It eventually naturalized in most of the U.S. It thrives in cottage gardens, meadows, woodland gardens, containers, slopes, and pondside. 

Comfrey Plant Identification

Comfrey is a clump-forming perennial that grows 1 to 3 feet (.30 to 1 meter) tall and spreads .75 to 2.5 feet (.23 to .76 m). Its dark green basal leaves are long and lanceolate (lance-shaped) while the upper leaves are shorter. The leaves and stems are covered in coarse hairs, and its stems are winged. Some gardeners consider comfrey weedy. 

Bell-shaped flowers in drooping clusters are borne on 2 to 3 foot (.61 to 1 m) stems. The comfrey’s flower color depends on the variety, but it can be pink, blue, yellow, or white and blooms appear from late spring to early summer. 

Care & Growing Conditions

Comfrey grows best in full to part sun in well draining, compost-rich soils that are kept moist, however, it does tolerate dry soils, as well as clay. Give it moderate water, allowing the soil to dry to a depth of 2 inches (5 cm). When comfrey is established, it can withstand periods of drought.

Aim for a pH between 6.0 and 7.0. Growing comfrey in areas with hot summers requires some afternoon shade. 

Once it’s planted, comfrey can be difficult to eradicate because any root pieces left in the soil will grow.

Comfrey Uses

Historically comfrey was taken orally to relieve internal ailments, but it’s no longer considered safe to consume because all its parts contain toxic alkaloids, particularly the roots. Continued ingestion of the plant can lead to severe liver problems, lung problems, and cancer. However, making a poultice from the leaves may be safe to use externally to help heal rashes, swelling, and bruises. 

Comfrey makes a great pollinator plant and is a favorite in bee gardens. Comfrey can be cut back several times during the season, and its prunings can be added to the compost pile where it supplies nutrients such as calcium, phosphorus, potassium, vitamins, and trace elements. 

Soaking comfrey leaves in water for at least a week produces a liquid fertilizer. Its potassium content benefits tomatoes. 

Planting Comfrey From Seed

Plant comfrey seeds outside ¼ inch (.64 cm) deep in a prepared bed about three weeks before the last spring frost. Comfrey also can be propagated by root division or plant division. 

Problems, Pests & Diseases

Comfrey is rarely bothered by pests or diseases and is deer-resistant, however, slugs or snails may dine on the foliage. 

Comfrey is considered invasive in the eastern U.S. Planting it in containers can help curtail its rapid spread.

Note: Comfrey is poisonous to humans.