Growing Guide
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Herbaceous Perennial Flower, Herb

Also known as Common Comfrey, Blackwort, Boneset, Healing Herb
Symphytum officinale
Boraginaceae Family

This coarse, spreading, perennial herb grows up to 4 feet tall and likes moist, somewhat shady locations. It has a long history as a medicinal herb but no culinary uses. Other species in this genus are more suited to ornamental plantings outside of the herb garden.

Site Characteristics
  • full sun
  • part shade
Prefers shade in warm areas.

Hardiness zones:

  • 3 to 9
Some of the related species or ornamental comfreys are only hardy to Zone 5.
Plant Traits

Lifecycle: perennial

Ease-of-care: easy

Height: 1 to 5 feet

Spread: 2 to 6 feet

Bloom time:

  • late spring
  • early summer

Flower color:

  • yellow
  • violet
  • white
  • pink

Ranges from purple-violet to pink, and creamy yellow to white.

Foliage color: dark green

Foliage texture: coarse

Shape: spreading mass

Shape in flower: same as above

Special Considerations
Special characteristics:
  • aggressive - Freely self-sows. Deep root system is difficult to eradicate. Even small fragments produce new plants.
  • non-invasive
  • not native to North America - Native to Europe, naturalized in North America.
Growing Information
How to plant:

Propagate by seed, division or separation - Plants are aggressive and readily self-sow. Plant seeds where you want them to grow in spring or fall, or sow in a cold frame and pot seedlings to be grown over the first winter inside.

Divide any time (spring is best) using a spade to chop off about 3 inches of root just below soil level. Plant divisions directly or pot them and overwinter before planting.

Maintenance and care:
Plants are very aggressive. Plant where they can spread without competing with other plants, or rein them in with a physical barrier.

Remove flowers to keep foliage looking nice. Deadhead plants to keep from spreading by seed.

More growing information: How to Grow Perennials

Leaf spot
Some related species of ornamental value include:

Caucasian comfrey (S. caucasicum) grows 2 feet tall and bears bright blue flowers in spring. Spreads aggressively. Zones 3-9.

Large-flowered comfrey (S. grandiflorum, S. ibericum) grows 1 to 1.5 feet tall and bears yellow flowers in spring. Spreads aggressively. Zones 5 to 9. (Some sources say hardy to Zone 3.) 'Variegatum' ('Goldsmith') has creamy margins and blue, cream or pink flowers.

Russian comfrey (S. x uplandicum) is a cross between S. asperum and S. officinale. It grows up to 6 feet tall and bears purple-blue flowers in late spring or early summer. Zones 4 to 8. (Some sources say hardy to Zone 3.) 'Variegatum' grows 3 feet tall, has gray-green leaves with creamy margins, and bears pale lilac blue to pink flowers.