General
Comfrey is a robust perennial herb used in permaculture and natural gardening for fast regrowth, large leaves, and its ability to accumulate nutrients (especially potassium) for mulch and liquid feeds. Many gardeners prefer the cultivar Symphytum × uplandicum 'Bocking 14' because it is sterile (does not set viable seed), making it less likely to spread by self-seeding while still producing abundant biomass.
Light
Full sun to partial shade.
Soil type
Deep, fertile, moisture-retentive but well-drained soil.
Water requirement
Medium to high; prefers evenly moist soil.
Nutrient requirement
Low; thrives even in poor soils once established.
Precultivation
Seed sowing is possible for fertile comfrey types (e.g., Symphytum officinale), but germination can be slow and irregular. The commonly grown cultivar 'Bocking 14' is sterile and is propagated vegetatively—typically by root cuttings or dividing established crowns—for reliable results.
Planting
Plant comfrey in a permanent location where its size and vigorous roots are welcome. Space plants generously and water well during establishment. If you’re planting 'Bocking 14', start from root cuttings/divisions and label plants, as it won’t come true from seed.
Pruning
Cut back leaves several times per season to control size and encourage fresh growth.
Maintenance
Very low maintenance once established. Water during prolonged drought, especially in the first year.
Harvest
Harvest leaves before flowering for best quality. Leaves are mainly used as mulch or fertilizer.
Common issues
Few problems; slugs may damage young plants. Fertile types can self-seed, while sterile types like 'Bocking 14' won’t spread by seed—but any comfrey can re-sprout from small root fragments if soil is disturbed, making removal difficult.
Pollination
Insect-pollinated, especially by bees.
Companion plants
Fruit trees, berries, tomatoes, squash, roses.
Incompatible plants
None known; can be overly competitive with small plants nearby.
