How to Grow Symphytum Plants

Guide to Growing Comfrey and Blackwort

Members of the Symphytum genus are hardy perennial herbs that range from 30 cm to 1.2 m in height 91 to 4 feet).

Depending upon the variety, they may bloom from the latter part of spring until the first frost of winter.

They have attractive varicolored leaves and carry clusters of small pink, blue, purple, white, or yellow bell-shaped flowers.

Common names for members of the genus include Blackwort, Knit-bone and Comfrey.

Symphytum officinale
Symphytum officinale by Matt Lavin.

If growing as a herb, then harvest the leaves after three years of growth, just before flowering occurs.

Symphytum Growing and Care Guide

  • Common Names: Comfrey, Blackwort, Boneset, knitbone, consound, Slippery-root.
  • Life Cycle: Hardy perennial.
  • Height: 12 to 40 inches (30—100 cm).
  • Native: Europe.
  • Growing Region: Zones 4 to 9.

  • Flowers: Late spring until the first frost.
  • Flower Details: Blue, cream, purple, yellow, pink. Bell-shaped. Tubular. Clustered. Nodding.
  • Foliage: Herbaceous. Variegated. Large. Elliptic. Erect stems.

  • Plant Outside: Grown from its rhizomatous roots. Bury at 3 to 6 inches (8—15 cm). Early spring or autumn. Space at 40 to 48 inches (100—120 cm).
  • Sow Inside: Full sunlight (for best results) or partial shade (leads to smaller plants). Rich, moist soil. Soil pH 6.5 to 7.5. Regular watering. Cut off dead leaves in the autumn.
  • If using for external medicinal herbal use, then harvest from plants that are at least three years old before blooming occurs.
  • Propagate: by taking root cuttings or by division in the spring or in autumn.

  • Requirements and care:
  • Family: Boraginaceae
  • Closely Related Species: Borage.
  • Miscellaneous: Used in traditional Austrian medicine to treat locomotor system and gastrointestinal tract disorders. Considered an invasive plant in many areas.

How to grow Blackwort, Comfrey and other Symphytum Plants

It is best to grow Symphytum plants from root cuttings; these should be buried in autumn or early spring at about 10 to 15 cm (4 to 6 inches) deep, with a spacing of about a metre.

Ideally they will grow in a sunny part of the garden where they will thrive: they tolerate shady conditions, and enjoy a rich soil of pH 6.5 to 7.5 that is kept moist.

Caring for Symphytum

Blackwort, Comfrey and other Symphytum take a little bit of caring for. They like a moist soil so keep well watered. Divide the plants every year to stop them growing too close together. In the autumn it is necessary to remove dead Blackwort leaves.

If you require more plants then they can be propagated by taking cuttings from the root in the spring, or easier still plant out divided plants when tidying up.

Common Questions

How many members does the Symphytum genus have?

The Symphytum genus includes about 35 species, most commonly known as comfrey.

Do members of Symphytum make a good garden or landscaping plant?

Symphytum can be a beneficial plant in the garden due to its ability to enrich soil and attract beneficial insects.

Which Symphytum species are most frequently grown by gardeners?

The most commonly grown species is Symphytum officinale, also known as common comfrey.

Are members of the Symphytum plant genus fragrant?

While not typically known for their fragrance, some people find the scent of comfrey's flowers to be quite pleasant.

What is the perfect location to grow Symphytum?

Symphytum prefers locations with full sun to partial shade and rich, well-drained soil.

Is Symphytum invasive in the USA, if so in which states?

Currently, Symphytum species are not considered invasive in the USA. Always consult local regulations for the most current information.

How do I remove Symphytum plants from my garden?

To remove Symphytum, dig up the entire plant including the root system, as small fragments can result in new plants.


The Symphytum genus includes perennial plants native to Europe and Asia. They are recognized for their bell-shaped flowers and large, hairy leaves. The leaves and roots of certain species are used in traditional medicine.

Grow Symphytum from seeds or root cuttings, ideally in spring. They thrive in full sun to partial shade and prefer well-drained soil. Regular watering is necessary, particularly during dry periods, and plants can benefit from regular applications of a balanced fertilizer.

I hope that you enjoyed this guide on how to grow Symphytum. You may also enjoy the following Boraginaceae growing guides: How to grow Brunnera macrophylla and Cynoglossum plants.