Comfrey

A deep-rooted perennial grown not to eat but to feed everything else. One planting of the sterile Bocking 14 cultivar gives a free, potassium-rich liquid feed and mulch for twenty years or more.

Written by Yemi · Last reviewed August 2026

Maturing this month

First sprouts in First leaves appear within 2–3 weeks of planting

Difficulty

Comfrey should be ready to harvest this month. Check for size and colour.

Growing Calendar

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Sow

Transplant

Bare-root / Sets

Harvest

This month: Sep

Log to journal

Ready to harvest now

•Check size and ripeness
•Harvest regularly
•Store or use fresh

Sowing Guide

What you'd find on the seed packet

Sow Depth

Crowns or root cuttings planted with the crown just below soil level

Spacing

60cm between plants

Germination

First leaves appear within 2–3 weeks of planting

Thinning

One crown per planting position; comfrey resents being moved once settled

Grower's Note

Almost always grown from root cuttings or crown divisions of the sterile Bocking 14 cultivar rather than seed, since ordinary comfrey seed produces a plant that self-sows and spreads.

Recommended Varieties

'Bocking 14' was bred in the 1950s by Lawrence Hills at Bocking, Essex specifically so it won't set seed and spread, while still producing the leaf growth needed for liquid feed or a compost activator, which is why it's the standard choice for a working comfrey patch. Bocking 14 plants are also sold by The Organic Gardening Catalogue, whose stock traces directly back to Frank Wood's original Bocking 14 plantation.

Planting Out Guide

Best spaces, conditions and how to plant out

Plant Spacing

60cm, allowing space to cut around the plant

Best Grown In

Open ground, a permanent out-of-the-way bed or a corner near the compost heap

Conditions

Full sun to partial shade. Tolerates poor soil and thrives on neglect once established.

Grower's Note

Pick the final position carefully: an established comfrey bed can be productive for twenty years, and any relocation risks leaving root fragments behind that will regrow.

Growing Stages

Approximate weeks from sowing to harvest

Sprouting

3wks

Seeds germinate and first leaves emerge. Keep warm and moist.

Establishing

20wks

Root system develops and plant builds structure. Pot on if needed.

Maturing

52wks

Plant reaches full size and begins producing. Harvest at peak.

Total~75 weeksfrom seed to harvest

Companion Plants

Plant these nearby for natural pest control, better yields, and healthier soil.

Apple

Repels Pests

Chopped comfrey leaves dropped as a mulch around the base break down quickly, releasing potassium as they rot down.

Tomato

Repels Pests

Comfrey's deep taproot draws up nutrients from the subsoil, making a potassium-rich liquid feed that suits heavy-fruiting Tomato well.

Raspberry

Repels Pests

A chop-and-drop mulch of comfrey leaves around the base feeds Raspberry canes through the fruiting season without needing a shop-bought feed.

Climate Control

Today

—C

Humidity

—%

Water

Every 3–4 days

Sunlight

6+ hours direct sun

Watch Out For

Choose the sterile Bocking 14 cultivar, not wild or common comfrey: ordinary comfrey sets seed freely and self-sows aggressively, becoming very hard to control

Any piece of root left in the soil will regrow: choose the final position carefully, since an established plant is extremely difficult to remove completely

The liquid feed smells strongly unpleasant as it ferments: brew it with a lid on and away from windows and doors, and always dilute before use, as the concentrate can scorch roots

What You'll Need

Equipment for growing comfrey

Modular Seed Tray

96-cell for precision sowing

Fine Rose Watering Can

Gentle shower for seedlings

Bamboo Canes

Pack of 20 × 120cm

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Grown Organically

Every method in this guide works with natural systems: no synthetic chemicals, no shortcuts.

Read our approach

Common Questions

About growing Comfrey in the UK

Is comfrey safe to eat?

Comfrey contains pyrrolizidine alkaloids linked to liver damage with regular internal use, so most modern growers treat it strictly as a feed and mulch plant rather than a food crop, despite historic use as a leaf vegetable.

How do I make comfrey liquid feed?

Pack cut leaves into a container with a lid, weigh them down, and leave for 3–5 weeks: the leaves break down into a strong, dark, strong-smelling concentrate. Dilute 1:10 to 1:15 with water before applying, since the neat concentrate is too strong and can scorch roots.

Why is Bocking 14 recommended over ordinary comfrey?

Bocking 14 is a sterile cultivar bred specifically for feed production: it produces very few viable seeds, so it stays where it's planted instead of self-sowing around the garden the way common comfrey does.

Can I grow comfrey in a container?

It's possible in a large, deep container, but comfrey's taproot can reach well over a metre down in open ground, which is where it draws up the minerals that make its feed so potent. A permanent ground position gets better results.

Written from real growing experience, not just research. Read the story behind Pelham Gardens.

Member guides

There's more to growing Comfrey than this guide covers.

A Garden Journal to log what worked, a personalised sowing planner in My Garden, and monthly reminders timed to the calendar.

See what's included