Florence fennel (Foeniculum vulgare var. azoricum) is the sophisticated, overachieving cousin of the common wild herb. While wild fennel is grown for its feathery fronds and seeds, Florence fennel is prized for its thick, crisp, bulb-like base.

It’s a cool-season vegetable that manages to taste like a cross between celery and black liquorice, bringing a refreshing "anise" crunch to the kitchen.

The Anatomy of the Plant Florence fennel is as much an ornamental beauty as it is a crop. It grows in a distinct, architectural fashion:

The "Bulb": This isn't actually a root bulb (like an onion); it is a collection of overlapping, swollen leaf bases that grow tightly together at the soil line. The Stalks: Tough, celery-like stalks rise from the bulb, which are excellent for flavouring stocks. The Fronds: At the top, you’ll find delicate, bright green, feathery foliage that looks almost like dill. These are packed with oils and make for a beautiful herb garnish.

Culinary Profile Fennel is a shapeshifter in the kitchen. Its flavour profile depends entirely on how you treat it:

Raw: When sliced paper-thin in salads, it is crunchy, watery, and has a bright, punchy liquorice flavour. It pairs famously well with orange segments and olive oil. Cooked: When roasted or braised, the anise flavour mellows significantly, becoming sweet, nutty, and almost creamy in texture. The "Waste-Not" Herb: Every part of the plant is edible. The seeds are a spice cabinet staple, the fronds are an herb, and the bulb is a vegetable.

The "Finicky" Factor

If fig trees are the resilient survivors of the garden, Florence fennel is the sensitive artist. It has a reputation for being slightly difficult for beginners because:

1. It’s a "Bolter": If the weather gets too hot or the plant gets stressed by lack of water, it will suddenly stop growing the bulb and send up a flower stalk instead. Once it "bolts," the bulb becomes woody and bitter.
2. Short Seasons: It prefers the steady temperatures of spring or autumn. In the UK, it’s often best sown in mid-summer for an autumn harvest to avoid the mid-July heatwaves.

How To Grow

Growing Florence fennel is all about management of stress. Because it is prone to "bolting" (flowering prematurely), the goal is to keep the plant cool, hydrated, and moving at a steady growth pace.

1. Timing is Everything Fennel is sensitive to day length and temperature. The Trap: Sowing in late spring (April/May) often leads to bolting because the plants hit the heat of June just as they are trying to bulb. The Pro Move: Sow in mid-to-late summer (June to July). This allows the bulb to swell as temperatures drop in the autumn, which produces a much sweeter, crisper harvest.
2. Sowing and Spacing Fennel has a long taproot and hates being moved. Direct Sow: Sow seeds directly into well-drained, fertile soil about 1 cm deep. Spacing: Space rows 30 cm apart. Once seedlings are about 5 cm tall, thin them out so there is 20–25 cm between each plant. Soil: They love rich soil. Dig in plenty of well-rotted compost or manure before planting.
3. The "Blanching" Technique To get those pearly white, tender bulbs you see in shops, you need to protect the base from the sun. When the bulb starts to swell (reaching the size of a golf ball), draw the surrounding soil up around the base of the plant. This process, called earthing up, keeps the bulb white, sweet, and protected from light frost.
4. Maintenance (The "Don'ts") Requirement Instruction Watering Never let the soil dry out. Inconsistent watering is the #1 cause of bolting and woody texture. Feeding Avoid high-nitrogen fertilizers late in growth, as this encourages leaf production over bulb swelling. Weeding Keep the area clear. Fennel doesn't like competition for moisture. Companion Planting Keep it isolated. Fennel is a bit of a "loner" in the garden and can stunt the growth of beans, tomatoes, and especially dill (they can cross-pollinate and ruin the flavour).
5. Harvesting You should be ready to harvest about 10–14 weeks after sowing. Size: Harvest when the bulb is roughly the size of a tennis ball or a large orange. Method: Use a sharp knife to cut the bulb just below the soil line, leaving the roots in the ground. Bonus: If you leave the root in the soil after harvesting the main bulb, it will often produce small, tender "fennel-lings" (side shoots) that are delicious in salads! Troubleshooting: Why did my fennel bolt? If your fennel sends up a tall flower spike and the bulb stays thin, it was likely caused by: Water Stress: Even one day of bone-dry soil can trigger it. Temperature Spikes: A sudden heatwave. Transplant Shock: If you started them in small pots and the roots got "root-bound" before planting.

How/When To Harvesting

To harvest Florence Fennel, timing is critical. If you wait too long, the bulb becomes "woody" and fibrous; if you go too early, you miss out on that satisfying crunch. Here is how to harvest your fennel for the best flavour and texture.

1. The "Size Up" Start checking your plants about 10–14 weeks after sowing. The Sweet Spot: Harvest when the bulb is roughly the size of a tennis ball (about 7–10 cm in diameter).Don't Wait Too Long: If the bulb starts to look elongated or a thick stalk begins to shoot up rapidly from the centre, it is about to bolt. Harvest it immediately, regardless of size.
2. The Cutting Technique You don't need to yank the whole plant out of the ground. Using a knife is cleaner and better for the soil. Clear the Soil: Brush away the "earthed up" soil from the base of the bulb. The Cut: Use a sharp, clean garden knife to cut the bulb just above the soil line. Leave the root system in the ground. Trim the Top: Cut the long stalks off about 2–5 cm above the bulb. Save the feathery fronds to use as a herb!3. The "Second Harvest" Bonus One of the best-kept secrets of fennel growing is the bonus crop. After you cut the main bulb, leave the root in the ground. If the weather stays mild, small "fennel-lings" (miniature side-shoots) will often sprout from the root. These are incredibly tender and sweet, perfect for tossing whole into salads.
3. Handling and Storage Fennel starts to lose its crispness the moment it is cut, as the water in the bulb begins to evaporate. Storage Method Timeline Best For...Crisper Drawer 3–5 days Wrap in a damp paper towel or put in a perforated bag to maintain humidity. Water Vase 1–2 days Stand the stalks in a glass of water (like celery) if using the fronds.Freezing6 months Blanch sliced fennel in boiling water for 1 minute first to preserve the colour.
4. Using the "Waste" The Stalks: They are often too fibrous to eat raw, but don't toss them! Throw them into a pot when boiling fish or making chicken stock for a subtle anise aroma. The Fronds: These wilt quickly. Use them immediately as a garnish for grilled sea bass, or chop them into a citrus vinaigrette.