Symphytum grandiflorum

Comfrey thrives in full sun or partial shade and grows best in fertile, moisture-retentive but well-drained soil, though it will cope with tougher conditions once established. Plant it where it can stay put, as the deep tap roots make it tricky to remove later.

Water well in its first season and during prolonged dry spells to keep growth lush. Apply a mulch of compost or well-rotted manure in spring to fuel strong leafy growth, and cut plants back to around 5cm (2in) above ground three or four times through summer for fresh foliage. Wear gloves when handling, remove spent flower stems if you want to limit self-seeding, and cut back fully in autumn once growth dies down.