How to Grow Comfrey: Planting, Harvesting and Comfrey Tea
Comfrey is one of the most useful plants in an organic garden: a free, fast-growing fertiliser you can cut four or five times a year. Plant Bocking 14 comfrey in a permanent spot in sun or part shade, let it establish for a year, then cut the leaves whenever they reach about 60 cm and use them as mulch, compost activator or liquid feed. This guide covers choosing, planting, harvesting and using comfrey in Irish and UK gardens.
Short on time? Choose the sterile variety. Our Comfrey Bocking 14 doesn't set seed, so it stays where you plant it instead of spreading across the garden.
Comfrey Quick Facts
Best variety: Bocking 14 (Symphytum Ă— uplandicum 'Bocking 14'), sterile and non-seeding
Planting time: spring or autumn
Spacing: 60 to 90 cm apart
Position: full sun to part shade, in a permanent spot
Soil: moist, fertile soil; tolerates most conditions
Height: up to 1.2 m
Cuts per year: 3 to 5, from the second year
Main nutrient: potassium, which helps flowering and fruiting
Why Grow Comfrey?
Comfrey's deep roots draw nutrients up from the subsoil into its large leaves. When you cut the leaves and use them around other plants, those nutrients are returned to the surface. The leaves break down quickly and are rich in potassium, which makes comfrey a natural feed for tomatoes, fruit bushes and fruit trees. Its flowers are also excellent for bees.
Comfrey is grown here as a garden plant and fertiliser, not for eating or teas for people.
Step 1: Choose Bocking 14
Common comfrey self-seeds freely and can become a weed. Bocking 14 was selected because it is sterile: it produces no viable seed and spreads only slowly from its roots. For a lower-growing option that works as ground cover under trees and in shade, dwarf comfrey forms spreading clumps 20 to 40 cm tall, though unlike Bocking 14 it will spread by seed.
Step 2: Plant It in a Permanent Spot
Comfrey is very hard to remove once established, as any piece of root left behind regrows. Choose its position carefully: a corner of the vegetable garden, near the compost heap, or around the edge of a fruit tree. Plant crowns 60 to 90 cm apart, water them in, and keep them weed-free while they settle.
A small patch of four to six plants gives plenty of leaves for an average garden.
Step 3: Let It Establish in the First Year
In the first year, let the plants build strong roots. Remove any flower stems and take only a light cut in late summer. From the second year, the plants will grow vigorously.
Step 4: Cut It Regularly
Cut the leaves when the plants reach about 60 cm, usually from April or May, leaving a few centimetres above ground. The plants regrow within weeks, giving three to five cuts a year until autumn. Wear gloves, as the bristly leaves can irritate skin. Stop cutting in early autumn so the plants can build reserves for winter.
Step 5: Use Your Comfrey
Mulch: lay fresh leaves around fruit bushes, fruit trees, potatoes and tomatoes. They break down within a few weeks and feed the soil.
Compost activator: add layers of leaves to your compost heap to speed up decomposition. Our guide on how to make compost explains how.
Comfrey tea: make a liquid feed for fruiting plants (below).
Planting holes: line potato trenches or bean trenches with a layer of chopped leaves.
How to Make Comfrey Tea
Fill a container with leaves: a bucket or barrel with a lid works well. Chop or crush the leaves to speed things up.
Weigh them down and cover with water: a brick or stone keeps the leaves submerged.
Leave for 3 to 5 weeks: the liquid turns dark brown and smells very strong, so keep the lid on and place it away from the house.
Strain and dilute: start with about 1 part comfrey tea to 10 parts water, and feed fruiting plants every one to two weeks in summer.
Tomatoes, peppers, courgettes, strawberries and fruit bushes all benefit. Our guide to growing tomatoes shows when to start feeding. Add the leftover sludge to the compost heap.
Troubleshooting Comfrey
Comfrey spreading where you don't want it: you may have common comfrey rather than Bocking 14. Dig out seedlings while small.
Plants hard to move: any root left behind regrows. Dig out as much as possible and cover the spot for a season.
Leaves covered in rust or mildew: common late in the season. Cut the plants back hard and they regrow cleanly.
Slow growth: comfrey is hungry. Mulch with compost or manure each spring.
FAQ: Growing Comfrey
What is comfrey Bocking 14?
Bocking 14 is a sterile variety of Russian comfrey (Symphytum Ă— uplandicum) selected by Lawrence Hills, founder of the Henry Doubleday Research Association (now Garden Organic), at Bocking in Essex. It produces no viable seed, so it spreads only slowly from its roots and doesn't self-seed around the garden. It's the variety most gardeners grow for mulch, compost and comfrey tea.
How often can you cut comfrey?
Once established, comfrey can be cut three to five times a year, whenever the plants reach about 60 cm. Leave a few centimetres above ground and the plants regrow within a few weeks. Let new plants establish in their first year with only a light cut, and stop cutting in early autumn.
What plants benefit from comfrey tea?
Comfrey tea is rich in potassium, so it's best for flowering and fruiting plants. Tomatoes, peppers, courgettes, strawberries, currants, gooseberries and fruit trees all benefit. Dilute it before use, starting at about 1 part tea to 10 parts water, and feed every one to two weeks through the summer growing season.
Where should I plant comfrey?
Plant comfrey in a permanent spot in full sun or part shade, as it's very difficult to remove once established. Good places include a corner of the vegetable garden, beside the compost heap, or around the edge of a fruit tree, where its leaves can be cut and dropped as mulch. Allow 60 to 90 cm between plants.
Grow Your Own Free Fertiliser
A few comfrey plants will feed your garden for decades, saving you money on bought fertiliser every year. Bocking 14 crowns from Earthling Plants are ready to plant this autumn. To see how comfrey fits into a full, self-feeding food forest design, it's all in The Complete Food Forest Blueprint.
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