It can be difficult to remove once established because even small pieces of root can grow into new plants.

No, it is not recommended for internal consumption due to liver toxicity risks.

Plant guide

Comfrey.

Symphytum officinale

Pronounced sim-FY-tum o-fi-shi-NAH-lee

Also known as Comfrey, Boneset, Common Comfrey

Comfrey is a hardy perennial herb known for its deep taproot and medicinal history. It is a favorite among gardeners for making nutrient rich liquid fertilizer. You will love how quickly it bounces back after being cut.

At a glance

Care level: Easy
Plant type: Perennial herb
Light: Full sun to partial shade
Indoor light: Direct sun
Water: Every 3 to 7 days
Mature size: 3 to 5 feet
Growth rate: Fast
Hardiness: USDA 3 to 9
Bloom time: Late spring to mid summer

Care

Plant this in a spot where it can spread, as it is quite vigorous. Keep the soil consistently moist and watch for wilting during dry spells. You can harvest the leaves multiple times a season for mulch or compost tea.

Watering: Keep the soil evenly moist but not waterlogged.
Feeding: Apply a balanced organic fertilizer during the active growing season.
Pruning: Cut back the foliage to the ground to encourage fresh growth.
Repotting: Comfrey is best grown in the ground, but if in a container, divide it when it becomes root bound.
Soil: Rich, moist, well draining soil
Soil pH: 6.0 to 7.0
Temperature: -35 to 30°C
Humidity: 40 to 70%
Drought tolerance: Moderate
Lifespan: Perennial, typically 10 plus years
Deer and rabbits: High

Signs it needs repotting

Roots growing out of the drainage holes
Stunted growth despite regular feeding

Safety

People: The plant is considered toxic if consumed due to the presence of hepatotoxic alkaloids.
Pets: This plant can be toxic to cats and dogs if ingested in large quantities due to pyrrolizidine alkaloids.
Children: Keep children away from the foliage as the rough hairs can cause skin irritation and the plant is toxic if eaten.
Contact allergens: The stiff hairs on the leaves and stems can cause skin irritation in sensitive individuals.
Airborne allergens: There is no significant evidence of airborne allergen risk.
Edibility: Comfrey contains pyrrolizidine alkaloids that can cause severe liver damage if ingested.

How to identify it

Large hairy lance shaped leaves
Clusters of bell shaped flowers
Deep black taproot system
Rough textured foliage surface

Height: 0.6 to 1.2m
Spread: 0.45 to 0.9m
Leaves: green, deciduous
Flowers: purple, pink, white, 1 to 2cm
Fruit: black, late summer

Problems to watch for

RustCommon
Slugs and SnailsCommon
AphidsUncommon
Powdery MildewUncommon

By symptom

Plant problems by symptom

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Growing it

Propagation: division, root cuttings, seed
When to plant: spring, autumn
Overwintering: The foliage will die back completely after the first hard frost. You can leave the dead material to protect the crown or clear it away for a tidy garden.
In containers: It is not well suited for containers due to its deep taproot and large size.

Root Division

1. Dig up a mature plant in spring or autumn.
2. Use a sharp spade to slice the root mass into smaller sections.
3. Ensure each section has at least one bud.
4. Replant the divisions immediately in moist soil.

Plant comfrey in a dedicated patch or under trees where you can easily harvest the leaves for mulch without disturbing the roots.

Grows well with

Apple · Comfrey is often planted under fruit trees to provide nutrients and suppress weeds.

Similar species

Russian Comfrey · This is a sterile hybrid that is more vigorous and less invasive than common comfrey.

Science

Family: Boraginaceae
Genus: Symphytum
Order: Boraginales
Class: Magnoliopsida
Native range: Europe and temperate Asia
Conservation: This plant is common and not of conservation concern.

It thrives in moist, nitrogen rich soils along riverbanks and in damp meadows.

Value to wildlife: nectar source
Pollinators: bees
Uses: green manure, liquid fertilizer, compost activator, medicinal poultice

Through the year

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Flowering

Fruiting

Foliage

Ecological indicators

Salinity: 2/9
Soil reaction: 6/9
Light: 6/9
Temperature: 5/9
Moisture: 7/9
Nutrients: 8/9

Taxonomy resolved against GBIF.

Questions people ask

Is comfrey invasive?: It can be difficult to remove once established because even small pieces of root can grow into new plants.
Can I eat comfrey?: No, it is not recommended for internal consumption due to liver toxicity risks.

Where the name comes from

The genus name Symphytum comes from the Greek word symphyo, meaning to grow together, referring to its historical use for healing bones. The specific epithet officinale indicates its historical status as a medicinal plant.

Good to know

Comfrey is often called knitbone because it was historically used to treat fractures.
The plant is a dynamic accumulator, pulling potassium and calcium from deep in the soil.
Comfrey leaves make an excellent liquid fertilizer when steeped in water.

Also in

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This guide was generated with AI on September 26, 2026 and checked against GBIF taxonomy. It is general information, not horticultural or veterinary advice. Read about how we build these guides.