How to grow Fennel in New Zealand
Fennel (Foeniculum vulgare) is a tall, feathery herb with an aniseed and liquorice flavour; its fronds, seeds and pollen are all used, and the bronze form makes a striking backdrop in the garden. Bulb or Florence fennel is a variety grown for its swollen base, and does best in cool weather. Fennel is a poor neighbour for most vegetables and self-seeds freely, so give it its own spot.
📖 Our full guide: How to Grow Fennel in New Zealand
At a glance
When to sow by region
| Region | When to sow | Regional note |
|---|---|---|
| Northland | February to April, August to October | |
| Auckland | February to April, August to October | |
| Waikato & Bay of Plenty | February to April, August to October | |
| Central North Island | February to April, September and October | Skip August in the central North Island. Hard frosts and cold soil stall seedlings, so start in September, under a cloche if you can. |
| Wellington & Lower North Island | February to April, August to October | |
| Nelson & Marlborough | February to April, August to October | |
| Canterbury | February, September to November | Sow Sep to Nov and Feb. Cover early sowings with a cloche or frost cloth, as frosts run to mid October. Get the last sowing in by Feb so it sizes up before winter growth stops. |
| Otago & Southland | September to November | Sow Sep to Nov. Cover early sowings with a cloche or frost cloth, as frosts run to late October. |
| Central Otago | October and November | Sow in October and November, covering October sowings on frosty nights, as frosts run into early November. Grow it for the leaf, as bulb types rarely size up before the autumn frosts here. |
Not to be confused with: Florence Fennel, the bulb-forming variety, which has its own page, and Dill, a similar feathery herb that cross-pollinates with fennel.
Where to plant
Grow fennel in full sun in fertile, free-draining soil that stays moist, ideally with a pH of 6 to 7; lime acid soil before sowing. Keep it away from most vegetables, especially tomatoes, beans and coriander, as it suppresses their growth, and away from dill, as the two cross-pollinate.
Herb fennel is a hardy perennial that self-seeds readily, and wild fennel has naturalised along roadsides and in open ground in many countries. Cut off flower heads before the seed ripens, or collect the seed, so it does not spread.
- Northland, Auckland, Waikato and Bay of Plenty, Wellington, and Nelson and Marlborough: sow from August to October and February to April. In warm areas, autumn sowing suits bulb fennel best.
- Central North Island: skip August. Sow in September and October and from February to April.
- Canterbury: sow from September to November, covering early sowings, and in February.
- Otago and Southland: sow from September to November.
- Central Otago: sow in October and November, covering October sowings on frosty nights. Grow it for leaf, as bulb types rarely size up before autumn frosts.
Choosing a variety
- Sweet or leaf fennel: a hardy perennial grown for its soft, feathery, aniseed-flavoured leaves and seeds, up to 1.5 m tall.
- Bronze fennel: tall bronze foliage for fronds, pollen and ornamental use.
- Bulb fennel such as Milano: an early, bolt-tolerant Florence fennel with big, white, round bulbs.
How to plant
- Sow seed directly, about 0.5 cm deep, where it is to grow; fennel dislikes transplanting.
- Keep moist; seedlings appear in 7 to 14 days.
- Thin to about 30 cm apart for herb fennel, or 30 cm in rows 45 cm apart for bulb fennel.
- For bulb fennel, mound soil around the base as the bulb swells to keep it pale and tender.
Watering and feeding
Keep the soil moist but do not overwater. Bulb fennel bolts if stressed by heat or dry soil. Mulch helps, and a light feed in a fertile bed is enough.
Pruning and care through the year
- Cut off flower heads before the seed ripens if you do not want fennel to self-seed.
- Cut herb fennel back in autumn or late winter; it regrows from the crown in spring.
Harvesting
Pick feathery fronds at any time, and gather pollen from open flowers on a dry day. Collect seed when the heads turn brown and dry.
Cut bulb fennel at ground level once the bulb is at least the size of a flattened tennis ball, before it splits or bolts. Bulbs keep up to a week in a bag in the fridge; use fronds within two days.
Growing in pots
Fennel is not ideal in pots, as a 30 cm pot holds only one plant. If you try, use a pot at least 30 cm wide and deep, in full sun, and keep it moist.
Using it
Use fronds with fish, in salads and as a garnish, fennel seed in breads, sausages and curries, and pollen as a finishing spice. Slice bulb fennel raw into salads, or roast, braise or add it to soups and stews.
Companion planting
Fennel is best grown on its own, away from the vege beds.
Keep apart
Avoid planting these close to fennel.
Pests and diseases
Fennel has few problems.
Pests to watch for
- Aphids New leaves distorted and yellow, with insects crowded on young shoots and sooty mould.
- Slugs Seedlings chewed, with slime trails.
Diseases to watch for
- Leaf spot Brown spots on fronds in wet weather; remove affected stems.
Common questions
Why is fennel bad for other plants?
Fennel suppresses the growth of many vegetables, including tomatoes and beans, so grow it on its own away from the vege beds.
What is the difference between fennel and Florence fennel?
Herb or sweet fennel is grown for its leaves and seeds and is perennial. Florence or bulb fennel is a variety grown for its swollen white base.
When do I sow fennel in New Zealand?
From August to October and February to April in most of the North Island and Nelson. In Canterbury and the south, sow in spring, and in Central Otago grow it for leaf.
Why did my bulb fennel bolt?
Heat, dry soil or transplanting stress make it bolt. Sow directly, keep it moist, and sow in autumn in warm areas.
Does fennel spread?
Herb fennel self-seeds readily and has naturalised in many places. Cut off flower heads before the seed ripens to keep it in check.
Can I grow fennel near dill?
Keep them apart. They cross-pollinate, which spoils the seed of both.
Sources we checked: Yates NZ: How to grow fennel; Yates NZ: Common problems of fennel; Kings Seeds: Fennel Sweet Leaf; Kings Seeds: Fennel Milano; Wikipedia: Fennel.