Comfrey Monograph

Comfrey

Symphytum officinale

Quick Reference

Common names: comfrey, common comfrey, knitbone, boneset
Latin name: Symphytum officinale
Plant family: Boraginaceae (borage family)
Parts used: leaves, roots
Primary actions: vulnerary, anti-inflammatory, demulcent, cell proliferant
Best preparations: poultice, compress, infused oil, salve, ointment
Safety rating: topical use only
Grown at Wild Clover Farm: yes — cultivated perennial

Botanical Description and Identification

Comfrey (Symphytum officinale) is a fast-growing perennial herb historically valued for its remarkable ability to support tissue repair. Known for centuries as “knitbone,” comfrey has been used externally to aid healing of wounds, sprains, bruises, and fractures.

Plant Characteristics

Leaves:
Large, lance-shaped leaves measuring 6 to 18 inches long. Leaves are rough, hairy, and deep green, with prominent veins. Basal leaves are the largest, while upper leaves become progressively smaller along the stem.

Flowers:
Drooping, bell-shaped flowers grow in clusters along arching stems. Flower color ranges from cream to pink or purple, depending on variety. Flowers bloom from late spring through early summer and are highly attractive to pollinators.

Stems:
Stems are thick, hollow, and covered with coarse hairs. Mature plants form dense clumps and may reach 3 to 4 feet tall.

Roots:
Thick, black-brown roots with a white interior. Roots are deep and brittle, breaking easily and regenerating new plants from fragments.

Identification Notes

Comfrey is easily recognized by:

• very large, rough leaves
• drooping tubular flowers
• coarse, hairy stems
• deep, regenerating roots

It may be confused with borage (Borago officinalis), which has blue star-shaped flowers and is an annual. True comfrey is a perennial with bell-shaped flowers.

Native Range and Habitat

Comfrey is native to Europe and parts of western Asia and has been widely cultivated elsewhere. It occasionally naturalizes near gardens, streams, and damp meadows.

Comfrey thrives in moist, fertile soil and tolerates partial shade. It prefers managed garden settings and does not typically spread aggressively by seed, though root fragments readily regrow.

Growing Comfrey

Climate and Growing Conditions

Comfrey grows well in USDA hardiness zones 3 through 9.

Sunlight:
Full sun to partial shade. Afternoon shade is beneficial in hot climates.

Soil:
Rich, deep, well-drained soil is ideal. Comfrey tolerates clay and heavy soils better than many herbs.

Water:
Moderate to high moisture is preferred, especially during establishment.

Temperature:
Cold hardy and resilient.

Propagation

From root cuttings:
Root cuttings are the most common propagation method. Even small root pieces readily regenerate into new plants.

By division:
Mature plants may be divided in spring or fall.

Spacing:
Plant 2 to 3 feet apart to allow for full growth.

Once established, comfrey is difficult to remove due to its deep roots. Choose planting location carefully.

Care and Maintenance

• Minimal fertilization required
• Cut plants back several times per season for regrowth
• Mulch to retain soil moisture
• Avoid disturbing roots unnecessarily

Comfrey has few pest or disease issues and is generally deer resistant.

Harvesting Comfrey

Leaves

Best time:
Harvest leaves just before flowering or during early bloom.

How to harvest:
Cut outer leaves at the base, leaving inner growth intact. Multiple harvests are possible each season.

Roots

Best time:
Fall after the first frost or early spring before new growth.

How to harvest:
Dig carefully and process promptly. Roots are extremely hard when dry and should be chopped while fresh.

Drying and Storage

Leaves:
Dry on screens or in bundles in a warm, dark, well-ventilated space until fully dry. Shelf life is one year.

Roots:
Chop into small pieces and dry thoroughly. Store in airtight containers. Shelf life is two to three years.

Traditional and Modern Uses

Comfrey has a long history of external use for injuries and tissue repair.

Primary Uses (External Only)

• Supports wound healing
• Reduces bruising and swelling
• Supports healing of sprains and strains
• Traditionally used for fractures and bone injuries
• Soothes inflammation and pain
• Promotes rapid tissue regeneration

Comfrey is used exclusively externally in modern herbal practice.

Energetics and Traditional Classification

• Temperature: cool
• Moisture: moist
• Taste: sweet, mucilaginous
• Tissue affinities: skin, bones, connective tissue, joints
• Energetic indications: tissue damage, inflammation, dryness, delayed healing

Comfrey is traditionally classified as a vulnerary and cell proliferant, strongly promoting tissue regeneration. It is indicated where repair is needed, particularly for bones, muscles, ligaments, and skin. Due to its rapid tissue-healing action, comfrey is used externally only in modern Western herbalism.

Primary Herbal Actions

• Vulnerary: accelerates wound and tissue healing
• Anti-inflammatory: reduces swelling and irritation
• Demulcent: soothes damaged tissue
• Cell proliferant: promotes rapid tissue regeneration
• Emollient: softens and moisturizes skin  

Preparation Methods

Comfrey Poultice

Fresh or dried leaves are moistened and applied directly to the affected area. Poultices are used for bruises, sprains, strains, and minor wounds.

Comfrey Compress

Strong tea made from leaves or root is applied externally using a cloth compress.

Comfrey Infused Oil

Dried leaves or root are infused in oil and used as the base for salves and ointments.

Comfrey Salve or Ointment

Salves are applied to intact skin for joint pain, muscle soreness, and injury recovery.

Safety and Contraindications

Comfrey contains pyrrolizidine alkaloids (PAs) that may cause liver damage if used internally.

• Do not use internally
• Use only on intact skin
• Avoid prolonged use on deep puncture wounds
• Do not use on infected wounds
• Avoid use during pregnancy and breastfeeding
• Use caution with liver disease

External use on closed skin is widely considered safe when used appropriately.

Wild Clover Farm Notes

At Wild Clover Farm, comfrey is grown intentionally for external medicine and garden use. Leaves are harvested several times per season and infused for salves used in first-aid and injury recovery.

Comfrey also serves as a valuable compost and mulch plant, returning minerals to the soil through its deep taproot.

Oklahoma/Zone 7 Growing Notes

• Extremely heat and drought tolerant once established, due to its deep taproot
• Grows year-round in Oklahoma; winter freezes knock it back but doesn't kill it; regrows quickly
• Can harvest 3-4 times per season; cut to 2 inches, it regrows
• Spreads from root pieces - any root fragment becomes new plant
• Plant comfrey along fence lines or property edges where spreading is acceptable - it's nearly impossible to eradicate once established, so site carefully

Foraging:

• Typically cultivated rather than wild
• Harvest leaves several times per season before flowering
• Roots are harvested in fall from mature plants
• Take only a portion of leaves to allow regrowth
• Use externally only

Common Questions

Can comfrey be used internally?
No. Modern use restricts comfrey to external applications only.

Can comfrey be used on open wounds?
Only briefly and with caution. It is best used on clean, superficial wounds or once wounds have begun to close.

References and Further Reading

• Hoffmann, David. Medical Herbalism
• Wood, Matthew. The Earthwise Herbal
• Tierra, Michael. Planetary Herbology

Disclaimer

This information is provided for educational purposes only and is not intended to diagnose, treat, cure, or prevent disease. Always consult a qualified health care provider before using herbal products, especially for injuries or chronic conditions.