How to grow Horseradish in New Zealand
Horseradish is a tough, hardy perennial grown for its thick, fiery root, grated fresh into sauces for roast beef, smoked fish and dressings. It is cold and drought tolerant and almost foolproof to grow, but it spreads from the smallest piece of root left in the ground, so give it a bed or a large pot of its own.
📖 Our full guide: How to Grow Horseradish
At a glance
When to sow by region
| Region | When to sow | Regional note |
|---|---|---|
| Northland | August to October | |
| Auckland | August to October | |
| Waikato & Bay of Plenty | August to October | |
| Central North Island | August to October | |
| Wellington & Lower North Island | August to October | |
| Nelson & Marlborough | August to October | |
| Canterbury | August to October | |
| Otago & Southland | October and November | Plant root cuttings Oct to Nov, once the soil has warmed and can be worked. |
| Central Otago | November and December | Plant root cuttings Nov to Dec, once the frosts are over and the soil has warmed. |
Where to plant
Plant horseradish in full sun or light shade in deep, fertile soil that holds moisture but drains well. Deep, loose soil gives long, straight, easy-to-dig roots.
Choose the spot carefully. Every piece of root left behind regrows, so once horseradish is planted it is very hard to remove. A dedicated corner, a raised bed or a large buried container keeps it under control.
- North Island, Nelson and Marlborough and Canterbury: plant root cuttings from August to October.
- Otago and Southland: plant in October and November, once the soil has warmed and can be worked.
- Central Otago: plant in November and December, once the frosts are over and the soil has warmed.
How to plant
- Get a root cutting, sometimes called a thong, about 15 cm long and as thick as a pencil or more, from a nursery or another gardener. Cut the top flat and the bottom at a slant so you know which way up it goes.
- Dig compost through the bed.
- Plant the root at a slight angle with the top about 2.5 cm below the soil surface.
- Space roots about 40 to 80 cm apart and water in well.
- When shoots appear, thin them to two or three per plant to encourage a thicker root.
Watering and feeding
Water regularly while plants establish, and weekly during hot, dry spells. Established horseradish is drought tolerant, but steady moisture gives bigger, juicier roots.
Top-dress with compost as growth starts in spring, with a light general feed or liquid feed through the growing season.
Harvesting
Roots are ready from about a year after planting. Dig in late autumn or winter after the foliage has died down or been touched by frost, when the flavour is strongest. Fork carefully around the plant and lift the main root.
If you want to clear the bed, dig out every piece, as the smallest fragment regrows. If you want a permanent supply, keep some side roots: replant them straight away or in spring for next year's crop.
Store whole, unwashed roots in a bag in the fridge for weeks. Grate horseradish in a well-ventilated spot, as the fumes are strong, and mix it with vinegar straight away, because it loses heat once exposed to air.
Growing in pots
A large, deep pot is the easiest way to stop horseradish spreading. Use a pot at least 50 cm wide and 70 cm deep, filled with quality potting mix, in sun or light shade. Water more often than in the ground, as pots dry out quickly. At harvest, tip the pot out, take what you need and replant a few pieces.
Propagation and saving seed
Horseradish rarely sets seed in New Zealand and is grown from root or crown cuttings. Take pencil-thick side roots about 15 cm long when you harvest, cut the bottom end at a slant, and replant them or store them in damp sand somewhere cool until spring.
Varieties
- Common Horseradish
- Variegated Horseradish
Companion planting
Horseradish is a long-lived perennial, so it suits the edge of a garden or orchard rather than a rotation bed. Traditional companion lists pair it with potatoes and fruit trees.
Good companions
- Potato The Herb Federation of New Zealand lists horseradish as a companion for potatoes; keep it at the edge of the bed so it does not invade.
- Apple Yates NZ lists apples and other fruit trees as companions; a clump at the edge of the orchard is easy to contain.
- Rhubarb Another long-lived perennial for a permanent corner of the garden.
Pests and diseases
Horseradish is rarely troubled by pests. Chewed leaves seldom affect the root crop.
Pests to watch for
- Aphids Clusters on young leaves and stems in spring.
- Flea beetle Lots of small round holes in the leaves, mostly on young growth in warm, dry weather.
Diseases to watch for
- Leaf spot Brown or grey spots on leaves in wet weather; remove the worst leaves.
Common questions
How do I stop horseradish taking over?
Grow it in a large, deep pot, a raised bed or a bottomless container sunk into the ground, and dig out every piece of root when you harvest unless you want it to regrow.
When do I harvest horseradish?
From about a year after planting, in late autumn or winter after the leaves die down, when the flavour is strongest. Dig what you need and replant a few side roots.
Can I grow horseradish from seed?
Not usually. It rarely flowers or sets seed in New Zealand, so it is grown from root or crown cuttings.
Why is my homemade horseradish not hot?
The heat comes from oils released when the root is grated, and it fades quickly once exposed to air. Grate it just before use, keep it cool, and mix it with vinegar straight away to hold its strength.
Are horseradish leaves edible?
Yes. Young leaves have a mild horseradish bite and can go into salads. Older leaves are tough.
Is horseradish safe to handle?
Grated fresh root can irritate skin and eyes, so wear gloves if you are sensitive and grate it in a well-ventilated spot.
Sources we checked: Yates NZ: How to grow horseradish; Herb Federation of New Zealand: Horseradish.