How to grow Celeriac in New Zealand
Celeriac (Apium graveolens var. rapaceum) is a celery grown for its swollen, knobbly base, which has a clean flavour somewhere between celery and parsley. It is easier than stalk celery but needs a long season of five to six months and steady moisture, so it pays to sow early. It does especially well in cooler southern gardens and stores well over winter.
📖 Our full guide: How to Grow Celeriac in New Zealand
At a glance
When to sow by region
| Region | When to sow | Regional note |
|---|---|---|
| Northland | August to October, January to April | |
| Auckland | August to October, January to April | |
| Waikato & Bay of Plenty | August to October, January to April | |
| Central North Island | August to October, January to April | |
| Wellington & Lower North Island | August to October, January to April | |
| Nelson & Marlborough | August to October, January to April | |
| Canterbury | August to January | Keep sowing through Nov to Dec with steady watering. Make the last sowing in Jan so the crop is ready before winter growth stops. |
| Otago & Southland | September to January | Sow Sep to Jan. Cover early sowings with a cloche or frost cloth, as frosts run to late October. |
| Central Otago | September to January | Sow Sep to Jan. Cover early sowings with a cloche or frost cloth, as frosts run to early November. |
Not to be confused with: Celery, the same species grown for its stalks rather than its root.
Where to plant
Grow celeriac in full sun or part shade in rich, well-drained soil that stays moist. It needs a long, steady season without drying out, which is why it suits cool, moist southern gardens so well.
- Northland, Auckland, Waikato and Bay of Plenty, the central North Island, Wellington, and Nelson and Marlborough: sow from August to October, or from January to April for a crop that matures in the cooler months.
- Canterbury: sow from August to January, keeping November and December sowings well watered. Make the last sowing in January.
- Otago and Southland and Central Otago: sow from September to January, covering early sowings with a cloche or frost cloth.
Choosing a variety
- Mars: a medium-early variety with good bolt tolerance and firm, tasty flesh, harvested at 7.5 to 10 cm.
- Giant Prague: the classic large, knobbly celeriac.
- Monarch: smoother skinned and easier to peel.
How to plant
- Sow seed thinly about 6 mm deep in trays of seed raising mix; it needs light and steady moisture to germinate.
- Keep moist; seedlings appear in 7 to 14 days.
- When seedlings are about 10 cm tall, transplant the healthiest 20 to 30 cm apart, in rows 40 to 60 cm apart, without burying the crown.
- Water in well and mulch with wood chips or pea straw.
Watering and feeding
Keep the soil moist at all times, especially in hot, dry spells. Dry soil gives small, tough roots.
Avoid fertilisers high in nitrogen, which grow leaves at the expense of the root. A balanced vegetable fertiliser or compost is enough.
Pruning and care through the year
- Remove side shoots from around the base as they appear, to help the root swell.
- Keep the bed weeded and mulched.
Harvesting
Lift celeriac once the roots are about the size of a tennis ball or larger, usually 20 to 28 weeks after sowing. Smaller roots are sweeter. Ease them up with a fork and trim off the leaves and fine roots.
In cool areas they can stay in the ground and be dug through autumn and winter. Stored in a cool, dark place, or in sand, they keep for 2 to 3 months; wrapped in the fridge, about two weeks.
Growing in pots
Celeriac can be grown in a pot at least 30 cm wide and deep, in full sun, mulched and kept constantly moist.
Using it
Peel celeriac and grate it raw into salads and remoulade, or roast, mash or purée it, add it to soups and stews, or mix it into mashed potato.
Companion planting
Celeriac stands in the bed for months alongside other slow crops.
Good companions
- Leek A slow, upright crop that shares the bed through autumn and winter.
- Beans Beans add nitrogen and grow alongside without crowding.
- Brassicas Cabbage family crops share the same cool-season bed.
Keep apart
Avoid planting these close to celeriac.
Pests and diseases
Slugs and aphids are the main pests of celeriac.
Pests to watch for
- Slugs Large ragged holes and slime trails, especially on young plants.
- Aphids New leaves distorted and yellow, with sooty mould.
- Whitefly Small white insects that fly up when disturbed, with stunted shoots.
- Carrot rust fly Tunnels in the root and stunted plants.
Diseases to watch for
- Leaf spot Brown spots on leaves; remove affected leaves and avoid overhead watering.
- Sclerotinia White, cottony mould and soft rot at the base in damp weather.
Common questions
How long does celeriac take to grow?
About 20 to 28 weeks from sowing, so it is a long-season crop. Sow early.
When should I sow celeriac in New Zealand?
From August to October, or January to April, in most of the North Island and Nelson, and from September to January in Canterbury and the south.
Why is my celeriac root small?
Usually dry soil or too much nitrogen. Keep it constantly moist, avoid high-nitrogen feeds and remove side shoots as they appear.
When is celeriac ready?
When the root is about the size of a tennis ball or larger. Smaller roots are sweeter.
How do I store celeriac?
Leave it in the ground in cool areas and dig as needed, or store the roots in a cool, dark place or in sand for 2 to 3 months.
Is celeriac easier than celery?
Yes, most gardeners find it easier, as it does not need blanching and is less fussy, though it still needs steady moisture.
Sources we checked: Yates NZ: How to grow celeriac; Yates NZ: Common problems of celeriac; Kings Seeds: Celeriac Mars.