Comfrey is several different plants under one name. One is a sterile hybrid grown to cut for liquid feed, one is a native wildflower that seeds itself about, and three are garden forms grown for their flowers and as ground cover. Picking the right one is about the job you want it to do.
Quick answer
Bocking 14 for liquid feed: it's sterile, so it won't seed around. Hidcote Blue for flowers in a border, creeping comfrey for low cover under shrubs, and tuberous comfrey for a wilder corner.
What Scotland means for the choice
Climate barely separates them. Every form here is rated H7The RHS's H1a–H7 scale for how much cold a plant can survive outdoors, H1a being tender indoor-only and H7 hardy anywhere in the UK. Full definition →, hardy below -20°C, and all of them die back in winter and regrow in spring. They all like consistently moist soil, which a wet Scottish summer supplies, so what decides the choice is how much each spreads and what you want from it. Damp growth also suits slugs, so watch young shoots in spring. The comfrey growing guide covers planting, cutting and making liquid feed.
| Form | Grown for | Size | Flowers | Spread risk |
|---|---|---|---|---|
| Bocking 14 | Liquid feed | Clump-forming | Purple-blue, summer | Low: sterile, no seed |
| Common comfrey | Liquid feed | Clump-forming | Purple, pink or cream, summer | High: self-seeds, regrows from root |
| Hidcote Blue | Borders, ground cover | Upright clump, about 45cm | Pale blue from red buds, spring | Moderate once established |
| Creeping comfrey | Ground cover | About 40cm tall, 0.5–1m spread | Cream from red-flushed buds, late spring to early summer | Moderate to high |
| Tuberous comfrey | Informal planting | 0.5–1m tall and wide; 2–5 years to mature | Pale creamy-yellow, hanging, early summer | Moderate to high |
None of them holds the RHS Award of Garden Merit.
For feed: Bocking 14
Bocking 14 is the comfrey to grow for liquid feed. It's a sterile hybrid, so it sets no seed and doesn't spread through the garden, and it stays in a clump that regrows after cutting. Because it has no viable seed, you buy it as a plant or grow it from root cuttings, crownsThe base of a perennial plant where roots and shoots meet, often sold and planted as a ready-made dormant plant rather than grown from seed. Full definition → or divisionPropagating a clump-forming perennial by digging it up and splitting it into several smaller pieces, each with roots and shoots attached. Full definition →. Common comfrey does the same job and can be grown from seed, but it self-seeds readily and regrows from any root left in the ground, so it's much harder to control. It's best kept to a large garden.
For flowers and ground cover
Hidcote Blue is the best all-round ornamental: an upright clump about 45cm tall with pale blue flowers opening from red buds in spring. It suits borders, cottage and wildlife gardens, banks and slopes, and grows in any aspect. Creeping comfrey is lower, about 40cm, spreading up to 1m, with cream flowers in one-sided hanging sprays, a good choice for ground cover under shrubs. Tuberous comfrey spreads by rhizomes and takes two to five years to reach full size, with small, hanging, pale yellow flowers that suit an informal or wild corner better than a tidy border. All three have tubular flowers that are popular with bumblebees.
Keeping it in check
Hidcote Blue, creeping and tuberous comfrey can all become a nuisance once established and need managing to keep them in bounds; dig out root pieces thoroughly when you remove them. All comfrey is harmful if eaten, and the hairy leaves can irritate skin, so wear gloves when cutting it.
Which one for your situation
- A patch to cut for liquid feed: Bocking 14.
- Flowers in a border, any aspect: Hidcote Blue.
- Low ground cover under shrubs: creeping comfrey.
- A wild or informal corner: tuberous comfrey.
- A native wildflower, with room to spare: common comfrey.
Common questions
Can I grow Bocking 14 from seed?
No. It's a sterile hybrid with no viable seed, so buy it as a plant or grow it from root cuttings, crowns or division. Common comfrey can be raised from seed.
Is Hidcote Blue invasive?
Less than common comfrey, which self-seeds, but it can still become a nuisance once established, so plant it where you can control it.
Can I make liquid feed from ornamental comfrey?
Bocking 14 and common comfrey are the ones grown for it. The ornamental forms aren't, and they're better left to flower.
Sources
Show the 6 sources
- Symphytum x uplandicum 'Bocking 14': Sterile, non-invasive, H7, habit, feed use
- Symphytum officinale (common comfrey): H7, self-seeding, flowers, containment
- Symphytum 'Hidcote Blue': Habit, height, flowers, aspect, garden uses, nuisance note
- Symphytum grandiflorum (creeping comfrey): Habit, height and spread, flowers, nuisance note
- Symphytum tuberosum (tuberous comfrey): Habit, size, 2-5 years to maturity, flowers, nuisance note
- How to grow comfrey: Common comfrey unsuitable for all but the largest gardens; seed propagation; harmful if eaten and skin irritation