Comfrey
symphytum officinale
Also known as: ["Common Comfrey","Knitbone","Blackwort"]
Overview
A perennial herbaceous plant native to Europe and Asia, known for its large, hairy leaves and bell-shaped flowers. It has a long history of medicinal use for treating wounds and bone fractures.
Benefits & Perks
["medicinal use","wildlife attractant (bees, butterflies, birds)","drought tolerant"]
Botanical Classification
| Phylum: | Magnoliophyta |
| Class: | Magnoliopsida |
| Order: | Boraginales |
| Family: | Boraginaceae |
| Genus: | Symphytum |
| Botanical Name: | Symphytum officinale |
Plant Characteristics
Basic Information
- Category: Herbs & Weeds
- Suitable Location: garden bed in partial shade, or container with adequate space
- Suitable For:
- Is Weed: No
- Allergenicity: low
Environmental Needs
- Climate: {"temperatureRange":"5–30°C"}
- Hardiness: {"zones":"3–8"}
- Misting: rarely required, only if ambient humidity is very low
- Drainage: Moderately well-draining; avoid heavy clay soils.
- Soil Type: Rich, fertile, well-draining soil with organic matter.
Maintenance Level
- Maintenance Level: moderate
- Toughness Level: high
- Pruning Frequency: After flowering; as needed to remove dead or damaged growth.
- Pruning Intensity: Light to moderate; avoid heavy pruning unless rejuvenating an old plant.
Care Details
Ideal Sunlight Coverage:
Partial shade to full sun (4–6 hours of direct sunlight or bright indirect light); prefers afternoon shade in hot climates.
Sunlight Tolerance Tips:
Acclimate plants gradually to direct sun; protect from intense midday sun; adjust placement based on seasonal light changes.
Care Requirements
Care Difficulty
easymoderate
Sunlight
partial shade to full sun
Morning sun is ideal; provide shade during peak heat; rotate pot for even growth.
Watering
every 7–10 days, allowing soil to dry slightly between waterings
Water thoroughly but infrequently; ensure soil dries slightly between waterings; avoid waterlogging.
Soil
rich, moist, well-drained loam
pH: Slightly acidic to neutral (pH 6.0–7.0).
Ensure good drainage; enrich with organic matter; avoid waterlogged conditions.
Temperature
Hardy in USDA zones 3–8; tolerates cold but prefers moderate temperatures (60–75°F); avoid extreme heat.
Protect from frost; avoid sudden temperature swings; maintain moderate humidity.
Fertilizing
every 4–6 weeks during growing season with balanced liquid fertilizer
Fertilize sparingly to avoid root burn; apply after watering; stop in late fall.
Propagation
Methods
Division or root cuttings; division is the most reliable method.
Step-by-Step Propagation Guide
- Divide clumps into sections with roots.
- Plant divisions at the same depth.
- Water thoroughly.
- Root cuttings: cut sections, plant horizontally, cover lightly, and keep moist.
Best Time: Early spring or fall when the plant is not in active bloom.
Environment
Warm, humid conditions with indirect light; keep soil consistently moist but not waterlogged.
Medium
Well-draining soil mix with added compost or peat moss.
Hormone
Not typically required for division; optional for root cuttings.
Timeline
Division: immediate establishment; root cuttings: 4–6 weeks for roots, 3–6 months to mature.
Tools Needed
Sharp knife, gloves, trowel, rooting medium.
Quick Tips
Divide every 3–4 years to maintain vigor; ensure each division has roots and shoots.
Pruning & Repotting
Pruning Guide
Method
Cut flower stalks at the base; trim back leggy stems to encourage bushier growth.
Pruning Plan
Remove spent flower stalks to encourage reblooming; thin overcrowded stems to improve air circulation.
Tools
Pruning shears, gloves, disinfectant.
Checklist
Disinfect tools; cut at an angle; remove dead/damaged growth; clean up debris.
Repotting Guide
Best Season
Early spring before new growth begins.
Pot Size
One size larger pot (e.g., +2–3 inches in diameter).
Method
Remove plant gently; trim roots if necessary; place in a slightly larger pot with fresh soil; water thoroughly.
Suggestions
Repot every 2–3 years or when the plant becomes root-bound; beneficial for container-grown plants.
Checklist
Check root health; prepare new pot; use fresh soil; water after repotting.
Advanced Care Tips
Watering Mastery
Watering Checklist
Check soil moisture; water deeply; ensure drainage; adjust for season.
How to Apply Water Properly
Water at the base of the plant, ensuring moisture reaches the root zone; allow excess water to drain away; water in the morning to reduce evaporation.
Watering Schedule Tips
Water deeply once the top inch of soil feels dry; reduce frequency in winter to prevent root rot.
Soil Improvement
Add compost or well-rotted manure; incorporate perlite or sand for drainage; avoid compacting soil.
Temperature Stress Management
Signs of Temperature Issues
Wilting, yellowing leaves, stunted growth, or leaf drop in extreme heat or cold.
Cold Stress
Slows growth; may cause leaf damage or dieback in prolonged freezing conditions.
Solution: Mulch heavily in winter; protect from frost; move potted plants indoors if temperatures drop below freezing.
Hot Stress
Leaves may scorch, wilt, or drop; growth may slow in excessive heat.
Solution: Provide shade during peak heat; increase watering; use mulch to retain soil moisture.
Fertilizing Guide
Fertilizing Checklist
Check season; dilute fertilizer; apply to soil; rinse tools after use.
Fertilizing Method
Use a balanced liquid fertilizer diluted to half strength every 4–6 weeks during growing season (spring to early fall); avoid fertilizing in winter.
Common Problems & Solutions
Toxicity Warning
Cats
ToxicSymphytum officinale is toxic to cats due to its pyrrolizidine alkaloid content, which can lead to severe liver toxicity and failure. Cats are particularly sensitive to such compounds.
⚠️ Symptoms:
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Dogs
ToxicThe pyrrolizidine alkaloids in Symphytum officinale are toxic to dogs, causing liver damage and potential failure. Prolonged ingestion can result in chronic liver conditions.
⚠️ Symptoms:
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Humans
ToxicSymphytum officinale contains pyrrolizidine alkaloids, which are hepatotoxic and can cause liver damage upon ingestion. Chronic exposure may lead to severe liver fibrosis and even cirrhosis.
⚠️ Symptoms:
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Frequently Asked Questions
Q: Is comfrey safe for human consumption?
A: No, comfrey contains pyrrolizidine alkaloids which can be harmful if ingested regularly or in large quantities.
Q: How is comfrey used medicinally?
A: Historically, it has been used topically as a poultice for wound healing and bone fractures due to its allantoin content.
Q: Does comfrey attract pollinators?
A: Yes, its bell-shaped flowers are attractive to bees and butterflies.
Quick Reference
| Family: | Boraginaceae |
| Care: | easy |
| Light: | partial shade to full sun |
| Water: | every 7–10 days, allowing so |
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