Fennel is best known for its aromatic aniseed flavour. Florence fennel is the most popular form, grown for its thick, swollen stems, which are used as a vegetable in roasts and salads. Fennel (or common fennel) does not form a bulb, but its decorative dill-like foliage is widely used to flavour or garnish dishes.
What you need to know about fennel
Name: Florence fennel, bulb fennel (Foeniculum vulgare var. azoricum), fennel, common fennel (Foeniculum vulgare), bronze fennel (Foeniculum vulgare ‘Purpureum’).
Height: Florence fennel, up to 1m; bronze fennel, up to 2m.
Plant type: annual vegetable or biennial herb.
Foliage: feathery, dill-like foliage.
Climate: warm and cool temperate.
Soil: well-drained, enriched with compost or well-rotted manure.
Position: full sun.
Flowering: aromatic yellow flowers.
Feeding: not required.
Watering: water regularly to keep the soil moist.
Appearance and characteristics of fennel
A highly decorative vegetable or herb with soft, dill-like foliage atop sturdy stems. Florence fennel produces a swollen stem at the base of the leaves and is ready for harvest when it swells to the size of a cricket ball.
Bronze fennel has gorgeous bronze-russet toned foliage that doubles as an ornamental plant. It is quite hardy and will tolerate growing in poor soils. Once established, it is drought tolerant, but will grow better when watered regularly.
How to use fennel
The leaves of both types can be used for flavouring dishes.
The bulb of Florence fennel is delicious roasted or sautéed with olive oil, where it caramelises to enhance its sweetness. A young fennel bulb can also be harvested earlier and finely shaved into salads.
How to grow fennel
Common fennel is considered a weed in some states, so it’s best to grow bronze fennel, which does not spread easily.
Choose a sunny spot with well-draining soil. Enrich the soil with plenty of compost and well-rotted manure, turning the bed over well to create a soft, friable surface for planting. Sow fennel seeds in spring or autumn. Florence fennel grows best when seeds are sown in early spring in warm climates, and mid-late spring in cooler climates. Keep the soil moist while plants are germinating. Thin fennel seedlings at least 25cm apart for adequate growing space.
Caring for fennel
Moisture stress or sudden changes in temperature can cause plants to bolt. Keep plants well watered and use an organic mulch to help conserve soil moisture.
Once the swollen bases of Florence fennel reach the size of a golf ball, use a cardboard collar or mound the soil to cover and blanch the growing stems. Blanching the stems can help reduce bitterness and give them the characteristic white bulb appearance. Remove flower stems as they appear, especially before harvest.
Leave the flowers on bronze fennel if you intend to collect the seed for cooking. The flavour tends to be stronger than the leaves, so a little will go a long way. Fennel cross-pollinates easily with dill, so don’t plant them together as the resultant seeds will not be as flavoursome.
How often should you water and feed fennel?
Water regularly to keep the soil moist. In hot periods, you may need to water every day.
Feeding is not necessary provided you thoroughly enriched the soil prior to planting.
Diseases and pests that affect fennel
Snails and slugs love the bulbs, so sprinkle snail bait (see our safety tip, below) around the garden bed to help deter them. Aside from them, fennel is virtually pest-free. Avoid overwatering as this can lead to issues with root rot.
How and when to harvest fennel
Harvest bulbs when they are the size of a cricket ball, or smaller if preferred. Simply cut just above the root with a sharp knife. Small, feathery shoots will emerge from the cut base and are great for use in salads.
Pick the fennel leaves as required for use. Though only take a handful at a time from Florence fennel, as it requires foliage for growth.
How to propagate fennel
Fennel grows best from seed sown direct where it is to grow. However, if raising seedlings, use biodegradable pots and transplant when young as they don’t like too much root disturbance.
Safety tip
After applying fertiliser, delay harvesting for a few days and rinse well before cooking and eating. If using products to deal with pests, diseases or weeds, always read the label, follow the instructions carefully and wear suitable protective equipment. Store all garden chemicals out of the reach of children and pets.
If you like this then try
Vietnamese mint: a pungent herb with spicy and peppery notes.
Italian flat-leaf parsley: another fragrant herb that’s ideal for cooking.
Spring onion: easy to grow and you can enjoy a harvest in just 8–10 weeks.
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