How to grow Florence Fennel in Australia

Where to plant

Grow Florence fennel in full sun in rich, moist, well-drained soil improved with compost. Anything that checks its growth tends to send it to seed without forming a bulb: cold snaps on young plants, dry soil, root disturbance and lengthening spring days all trigger bolting. That is why late summer and autumn sowings, which form their bulbs as the days shorten and cool, are the most reliable in Australia.

• South East Queensland and the Northern Rivers: sow from February to May.
• Sydney, Melbourne and Adelaide: sow from February to June for bulbs through winter. Autumn sowings give the best results.
• Perth: sow from March to June for winter bulbs.
• Canberra: sow from December to February so the bulbs form in the cool autumn. Spring sowings bolt in summer heat.
• Hobart: sow from November to January for autumn bulbs. Spring sowings bolt after cold nights.
• North Queensland and Darwin: our calendar marks these as unsuitable, as Florence fennel bolts quickly in tropical heat.

Choosing a variety

Choose a variety described as slow to bolt or bolt resistant, especially for any sowing outside the main autumn window. Finale and Di Firenze are commonly sold in Australia. Even bolt-resistant varieties can still bolt in dry or cold conditions.

How to plant

1. Sow seed direct, about 1 to 1.5 cm deep, in rows about 30 cm apart. Direct sowing avoids the root disturbance that can cause bolting.
2. If you start seed in punnets or cells, transplant while the seedlings are small and handle the roots gently.
3. Keep the soil moist until seedlings appear, usually in about 10 days.
4. Thin to about 25 to 30 cm apart for full-sized bulbs, or 10 to 15 cm for small bulbs.
5. Mulch once the plants are established.

Watering and feeding

Water regularly and generously, and never let the soil dry out completely. Even moisture is the single biggest factor in getting a bulb rather than a flower stalk.

Feed lightly with a liquid fertiliser every few weeks through growth. Soil already rich in compost needs little more.

Pruning and care through the year

• When the bulbs start to swell, mound soil or mulch up around them to blanch them, which makes them whiter and sweeter.
• Keep the bed weeded, as young fennel competes poorly.
• If a plant starts to send up a tall central flower stem, harvest it straight away, as the bulb turns tough and stringy once it bolts.

Harvesting

Harvest when the bulbs are about 10 to 15 cm across, usually about three months after sowing, or earlier for small, tender bulbs from about 5 cm. Cut the bulb just above the soil. The stump left behind will not form another bulb, but it often sends up small, leafy shoots you can use like herb fennel.

Trim the leaves and stalks and keep the bulbs in a bag in the fridge for up to a week. The feathery fronds wilt quickly, so use them within a day or two.

Growing in pots

Florence fennel can be grown in a pot at least 30 cm wide and deep, in a quality potting mix. Pots dry out fast, and dry fennel bolts, so water often and feed lightly every couple of weeks. Choose a compact or bolt-resistant variety.

Using it

Slice the bulb thinly and eat it raw in salads with citrus, or roast, braise or grill it, which makes it soft and sweet. The fronds are used like a herb with fish.