How to grow Comfrey in New Zealand
Comfrey is a vigorous, deep-rooted perennial with large, hairy leaves and drooping bell-shaped flowers that bumblebees love. Gardeners grow it as a living fertiliser: the leaves are rich in potassium and other nutrients drawn up from deep in the soil, and they can be cut several times a year for mulch, compost or a liquid feed. Plant it where you want it to stay, as even small pieces of root regrow.
📖 Our full guide: How to Grow Comfrey in New Zealand
At a glance
When to sow by region
| Region | When to sow | Regional note |
|---|---|---|
| Northland | August to May | |
| Auckland | August to May | |
| Waikato & Bay of Plenty | August to May | |
| Central North Island | August to May | |
| Wellington & Lower North Island | August to May | |
| Nelson & Marlborough | August to May | |
| Canterbury | August to May | |
| Otago & Southland | September to April | Plant Sep to Apr so roots establish before the hard frosts. |
| Central Otago | September to March | Plant Sep to Mar so roots establish before the hard frosts. |
Where to plant
Comfrey grows in sun or part shade in most soils, and is most productive in moist, rich ground. Choose its spot carefully: it is deep rooted and any piece of root left in the soil regrows, so it is very hard to remove once established. A corner near the compost heap or under fruit trees is ideal.
- Northland, Auckland, Waikato and Bay of Plenty, the central North Island, Wellington, Nelson and Marlborough, and Canterbury: plant from August to May.
- Otago and Southland: plant from September to April so roots establish before the hard frosts.
- Central Otago: plant from September to March.
Choosing a variety
- Bocking 14: a sterile Russian comfrey that does not set seed, so it will not spread across the garden by seed. It is the usual choice for mulch and liquid feed, grown from root cuttings or crowns.
- Common comfrey (Symphytum officinale): sets seed and can spread, so it is best avoided in small gardens.
How to plant
- Plant root cuttings or crowns about 5 cm deep, or plant a potted plant at the same depth it was growing.
- Space plants about 60 cm apart.
- Water in well and keep moist while they establish.
Watering and feeding
Water young plants in dry spells. Established comfrey is deep rooted and copes with dry weather, but regular moisture gives more leaf. A dressing of compost or manure in spring keeps it productive.
Pruning and care through the year
- Cut plants back several times a season once established. They regrow quickly.
- Remove flower stems on common comfrey before seed sets, to stop it spreading.
- To propagate, slice through the clump just below the soil surface with a spade and replant the pieces.
Harvesting
Cut the large leaves once the plant is established, ideally just before flowering when they are richest in nutrients, and several times through the growing season. Wear gloves, as the hairy leaves can irritate skin.
Growing in pots
Comfrey can be kept in a large pot at least 30 cm wide and deep, which stops it spreading. Keep it watered and cut it regularly.
Using comfrey in the garden
Chop and drop: lay cut leaves as a mulch around fruit trees, tomatoes and potatoes, keeping them clear of stems, where they break down quickly and feed the soil.
Liquid feed: pack leaves into a bucket or drum, cover with water and a lid, and leave for a few weeks until the liquid is dark. Dilute it well with water and use it as a potassium-rich feed for fruiting plants.
Compost: add leaves to the compost heap to speed it up.
Comfrey contains pyrrolizidine alkaloids that can damage the liver, so do not eat it or drink it as a tea.
Propagation and saving seed
Bocking 14 is sterile, so it is grown from root cuttings or by splitting the crown. Pieces of root regrow very readily, which makes new plants easy but also means unwanted plants are hard to get rid of.
Companion planting
Comfrey is grown near the plants that benefit most from its leaves as mulch and feed.
Good companions
- Tomato Comfrey leaves and liquid feed are rich in potassium, which tomatoes need for fruit.
- Potato A traditional pairing; comfrey leaves laid in the trench or as mulch feed the crop.
- Fruit trees Planted near fruit trees, it supplies chop-and-drop mulch for the root zone. Keep it clear of the trunk.
- All plants (chop-and-drop mulch) (its leaves can be cut and laid around any plant as a mulch that feeds the soil as it breaks down)
Pests and diseases
Comfrey is almost trouble free. The main problem is the plant itself spreading where it is not wanted.
Comfrey is rarely troubled by pests.
Diseases to watch for
- Rust Orange pustules on leaves in late summer; cut the plant back and let it regrow.
Common questions
Is comfrey invasive?
It is hard to remove once established, as any piece of root left in the soil regrows. Grow the sterile Bocking 14, which does not spread by seed, and plant it where you want it to stay.
How do I make comfrey tea fertiliser?
Pack leaves into a container, cover with water and a lid, and leave for a few weeks. Dilute the dark liquid well with water and use it to feed fruiting plants such as tomatoes.
Can you eat comfrey?
No. Comfrey contains pyrrolizidine alkaloids that can damage the liver, so it should not be eaten or drunk as a tea.
How often can I cut comfrey?
Several times a season once established. It regrows quickly after each cut.
What is Bocking 14 comfrey?
A sterile Russian comfrey that does not set seed, so it will not spread by seed. It is grown from root cuttings and is the usual choice for gardens.
When should I plant comfrey?
From August to May in most regions, and September to April in the colder south, so roots establish before hard frosts.
Sources we checked: Wikipedia: Comfrey; Kings Seeds: Organic comfrey spray; Garden Organic: Comfrey.