Comfrey is a deep-rooted perennial herb grown mainly as a soil amendment and mulch source rather than for direct culinary use. Its taproot pulls nutrients from deep in the soil, and the leaves break down quickly, making it a common choice for compost activation and homemade liquid fertilizer.
It spreads aggressively and is difficult to remove once established because root fragments resprout. Plant it where you want it permanently, or choose the sterile 'Bocking 14' cultivar to limit self-seeding. Cut leaves several times per season; the plant regrows fast and benefits from repeated harvest.
Comfrey Rust
Orange to brown pustules on the undersides of leaves; yellowing and distortion of foliage. Severe cases weaken the plant and reduce leaf yield.
Cut back and destroy infected foliage; do not compost it. Improve air circulation and avoid overhead watering. Comfrey usually regrows healthy after a hard cutback.
Powdery mildew
White or grey powdery coating on leaves — usually starting on older growth in humid conditions or when nights cool.
Improve air circulation by thinning plants. Apply neem oil or potassium bicarbonate spray at first sign. Avoid overhead watering.
Slug and Snail Damage
Large irregular holes chewed in leaves, with slime trails on foliage and soil.
Hand-pick at night, set beer traps, or apply iron phosphate bait. Remove debris and mulch where they hide.