Foeniculum vulgare (Azoricum)
Florence fennel produces a swollen, aniseed-flavoured bulb at the base of its feathery foliage. Roasted or raw in salads, it is one of the great Italian kitchen vegetables. It bolts at the slightest provocation, which makes timing everything — sow too early and the plants run to seed before forming a bulb. Get the timing right and you are rewarded with one of the most elegant and versatile vegetables the kitchen garden produces.
Florence fennel (Foeniculum vulgare var. azoricum) is a distinct vegetable crop, unrelated to herb fennel though sharing the same aniseed character. The swollen stem base — the 'bulb' — is the edible part, though the feathery leaves and seeds are also excellent. All UK-suitable varieties are bolt-resistant F1 hybrids or named open-pollinated selections; avoid generic unnamed seed which has poor bolt resistance. The key decision is sowing date: mid-June to mid-July gives the most reliable results across most UK regions, as shortening days from late July reduce the photoperiodic trigger for bolting.
The number of varieties shown for each crop is based on UK consumption data (2025/26) — the more popular the crop, the more variety choices we include.
Open-pollinated varieties that have proven themselves in UK kitchen gardens over many years. Large, flavourful bulbs with reliable bolt resistance. Good for gardeners who prefer saving seed or sourcing from heritage suppliers.
The most widely grown Florence fennel in the UK. Very large, round, pure-white bulbs with outstanding bolt resistance. Vigorous and reliable across all UK regions. The benchmark bolt-resistant open-pollinated variety and the first choice for most UK kitchen gardeners.
Small, round, compact white bulbs. Among the most bolt-resistant varieties available for UK conditions. Good for gardeners who have struggled with fennel bolting in previous seasons. The compact size suits smaller plots and closer spacing.
An early-maturing open-pollinated variety with particularly good bolt resistance for a heritage type. Produces compact, well-rounded, pure white bulbs with excellent anise flavour. One of the most widely recommended heritage fennels for UK conditions. Reliable from June sowings onwards.
Bred specifically for maximum bolt resistance, uniformity, and reliable performance in UK summer conditions. Essential for June and July sowings where day length and temperature fluctuations present the greatest bolting risk. Consistent shape and size.
Modern F1 hybrid with very uniform, large bulbs and strong bolt resistance. Particularly good for late sowings (July). Consistent shape makes it attractive for exhibition and market growers. One of the most widely available F1 fennels in UK seed catalogues.
Compact, early-maturing F1 variety with good bolt resistance. Smaller and rounder than Orion, making it a good choice for smaller garden plots and successional sowings. Reliable performance across a range of UK conditions.
Very white, smooth, well-rounded bulbs with good bolt resistance for UK summer sowing. Uniform, clean appearance. A reliable commercial-grade variety that also performs well in the kitchen garden. Good choice for late June to mid-July sowings.
Upright, slightly elongated white bulbs with particularly good bolt resistance. One of the most reliable varieties for later UK sowings (mid-July). Consistent cropper in variable summers and well suited to northern regions where the growing season is shorter.
Very smooth, pure white rounded bulbs with tight form. Excellent uniformity and strong bolt resistance. Particularly good for successional sowing through June and July. Clean appearance and reliable performance across UK conditions.
Large, uniform white bulbs with outstanding roundness and commercial-grade consistency. Strong bolt resistance. One of the most reliable performers for later UK sowings. Upright feathery tops make for an attractive and productive plant.
Florence fennel seed is widely available from all major UK seed companies. Named bolt-resistant varieties such as Romanesco, Zefa Fino, and Orion F1 are widely stocked. Specialist seed companies carry heritage open-pollinated varieties. Plug plants are occasionally sold by garden centres in May — resist the temptation, as these are almost always sown too early and will bolt.
Rake to a fine tilth and incorporate a balanced general fertiliser. Florence fennel prefers a light, well-drained soil — on heavy clay, work in horticultural grit and compost to improve drainage. Avoid recently manured ground.
Draw drills 1cm deep, 30cm apart. Water the drills before sowing if the soil is dry. Fennel germinates best in warm soil at 18–20°C — sowing into dry soil delays germination and stresses seedlings.
Sow 3–4 seeds together at 25cm intervals. Cover with fine soil and firm gently. Germination takes 7–14 days in warm conditions. Do not cover with fleece — fennel needs warmth but also air circulation.
Firm the soil surface gently along the row with the flat of your hand. Water in with a fine rose. Mark the row ends with canes — young fennel seedlings are thread-fine and easy to miss amongst weeds.
Germination takes 7–14 days at 18–20°C. The first seedlings appear as tiny thread-like feathery shoots. Keep the seedbed evenly moist during this period — any drying out can kill germinating seeds.
Once seedlings reach 5cm, thin to the strongest plant at each station. Cut unwanted seedlings at soil level with scissors — pulling risks disturbing the roots of the plant you wish to keep.
When the swelling base becomes visible above the soil, draw soil up around it to the height of the lowest leaf joints. Repeat every 10 days. This blanches the bulb, making it whiter and sweeter.
Harvest when bulbs reach tennis-ball size, typically August to October. Cut just below the soil surface with a sharp knife. The feathery fronds can be used as a herb.
| Region | Sow / plant | Harvest | Notes |
|---|---|---|---|
| Scotland & Far North | Jul | Jul–Sep | Short season makes Florence fennel marginal. Sow early July only; fleece from September to extend harvest. · Jul only (direct) |
| Northern England | Jun–Jul | Jul–Oct | July sowings most reliable. Harvest September–October before first frosts. · Late Jun – mid-Jul (direct) |
| Midlands & Wales | Jun–Jul | Aug–Oct | Mid-June to mid-July sowing window. Harvest August–October. · Mid-Jun – mid-Jul (direct) |
| Ireland & Isle of Man | Jun–Jul | Aug–Oct | Similar to Midlands. Choose the most sheltered, warmest spot available. · Mid-Jun – mid-Jul (direct) |
| South & SE England | Jun–Jul | Aug–Nov | Best conditions in the UK for Florence fennel. June to late July sowing; harvest August to November. · Jun – late Jul (direct) |
| South Coast & SW | Jun–Aug | Aug–Nov | Longest season. Harvest can extend into November. Still avoid spring sowings. · Jun – early Aug (direct) |
Florence fennel should never be started in a propagator or indoors — it must be sown direct in its final position. Any root disturbance at transplanting stage triggers bolting. A propagator is not used for this crop.
Not applicable — sow direct outdoors only from mid-June.
Not applicable — sow direct outdoors only from mid-June.
Consistent moisture is critical. Irregular watering is one of the main triggers of bolting. Water deeply once or twice a week in dry weather rather than shallow daily watering. Do not let the soil dry out as bulbs are forming.
When the swelling base is visible above the soil (golf-ball size), draw soil up around it every 10 days until covered to leaf-joint level. This blanches the bulb, making it whiter and sweeter. Do not bury the leaves.
Cut just below the soil surface when bulbs reach tennis-ball size. Leaving them too long risks bolting in warm spells. After harvest, the stump will sometimes resprout producing small secondary buds worth cutting and using.
Bolting is the defining challenge of Florence fennel. It is triggered by cold temperatures, root disturbance, drought stress, or sowing too early. Once a plant bolts the bulb will not develop — harvest immediately and use in cooking even if small. Never transplant fennel; always sow direct. Keep fennel isolated from the main vegetable garden where possible as it is allelopathic to many crops.
Full identification and treatment advice is in the Pests and Diseases sections.
Wrap bulbs in damp paper towel and place in a sealed bag or container in the vegetable drawer. Trim any discoloured outer layers before use. Use within 5–7 days — fennel loses its sweetness quickly after harvest.
Florence fennel is outstanding eaten raw. Slice paper-thin on a mandoline with fronds for a classic Italian salad with orange and olive oil. The aniseed flavour mellows dramatically when sliced thinly.
Cooked fennel — braised, roasted, or griddled — keeps well in the fridge for 3 days and reheats excellently. Cooking mellows the aniseed flavour considerably. Roasted wedges at 200°C for 30–35 minutes is the simplest and finest preparation.
Counterintuitively, sowing in early-to-mid July produces better results than sowing in June across most UK regions. Longer, warmer days in late July and August support faster, more reliable bulb swelling, and the shortening days from August reduce the photoperiodic bolting trigger. If June sowings have let you down in previous years, move the whole operation to the first week of July.
Florence fennel is one of the few vegetable garden crops that is genuinely allelopathic — its root exudates suppress the germination and growth of most neighbouring plants. Grow it in its own bed or at the very edge of the vegetable garden, well away from tomatoes, legumes, and brassicas. This is not a companion planting preference — it is a chemical effect that will reduce yields of neighbouring crops regardless of care.
The feathery green fronds cut at harvest are outstanding as a herb — stronger and more aromatic than anything sold commercially, with a clean, fresh aniseed character. Scatter over grilled fish, stir through salad dressings, or use as a garnish for roasted vegetables. The fronds deteriorate quickly after harvest so use immediately. A second flush of fronds sometimes regrows from the cut stump and is equally good.