Florence fennel grows best during warm summers and needs an open, sunny site. Prepare a seedbed in fertile, well-drained soil, adding plenty of well-rotted organic matter the winter before planting. It thrives on warm, moist, fertile, sandy soils.
The plants dislike root disturbance. Sow in cooler climates or, for early crops, better to sow in modules as single seedlings to avoid root damage. Plant out modules as soon as possible once the roots fill container from April, ‘harden off’, then plant out once the soil is warm and there is no danger of frost, from early May onwards. Early sowings are very liable to flower prematurely (bolt); there are bolt-resistant cultivars.
Alternatively, sow directly into the soil, 1.5mm (½in) deep in rows 30cm (12in) apart, thinning to 30cm (12in) apart in the rows when the soil is warm from May to early July. Use bolt-resistant cultivars for mid-June to mid-July sowings.
Provide plenty of moisture throughout the growing season, keep weed free and mulch to conserve moisture.
Earth up (mound soil) round the bulbs as they start to swell, from mid-summer until mid autumn, until the bulb is mature and about 7-10cm (3-4in across) to blanch the bulbs and to exclude autumn frosts.
Feed with high potassium fertiliser every two weeks once established.
The largest bulbs are formed in warm, sunny, moist summers.
Slugs and snails: These feed on the young seedlings and you'll see the tell tale slime trail on the soil around your crop, as well as on the leaves.
Remedy: There are many ways to control slugs and snails, including beer traps, sawdust or eggshell barriers and copper tape.
More info on Slugs and snails
Bolting: Plants flower and set seed, rather than producing edible roots. This is usually caused by stress – a cold spell or drought.
Remedy: Sow bolt-resistant varieties and keep the soil moist.
More info on Bolting
Small bulbs: Small bulbs grown; only a small part of the bulb is white.
Remedy: Ensure that they are earthed up properly and maintain moisture levels in the soil.
Around 20 days after ‘earthing up’, cut the bulbs off at ground level. They will then re-sprout and the small shoots can be used in salads.
'Perfection’: Produces medium sized bulbs with a delicate aniseed flavour. Resistant to bolting and ideal for early sowing.
‘Cantino’: Has a refreshing aniseed flavour. Bolting resistant.
‘Amigo’ AGM: Produces uniform, slightly flattened bulbs. Bolting resistant.
‘Heracles’ AGM: Fast maturing, with moderately sized, flattened bulbs.
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