Florence fennel, a wonderfully ornamental vegetable, is grown for its swollen leaf bases or ‘bulbs’ and edible leaves. When using in salads, the flavour can be improved by slicing the bulb and putting it in a bowl of water and ice cubes in the fridge for an hour. Steam, grill or boil the ‘bulbs’ and serve with cheese sauce or butter; infuse the leaves in vinegar or add as garnish to salad.
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, 15mm (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.
Troubleshooting Growing Problems
Bolting: Plants flower and set seed prematurely.
Remedy: Unless growing for seed sow bolt-resistant varieties. Sow or plant at the correct time and keep the soil or compost moist.
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, copper tape and biocontrols.
Birds: Birds, especially pigeons, can cause an array of problems including eating seedlings, buds, leaves, fruit and vegetables.
Remedy: Protect the plants from birds by covering them with netting or fleece. Scarecrows and bird-scaring mechanisms work for a while, but the most reliable method of protection is to cover plants with horticultural fleece or mesh.
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.
Fennel is a highly aromatic and slightly odd plant that is pretty much a poor companion plant for everything.