Growing Florence Fennel in Scotland: The Complete Guide

Foeniculum vulgare var. azoricum

Florence fennel has a reputation for being tricky, and it is earned: cold, disturbed roots and dry soil each push it to bolt instead of forming a bulb. Each of them can be avoided.

It does best in warm, damp summers. In Scotland the damp usually comes easily and the warmth is what to protect, so treat every precaution below as necessary rather than optional, because skipping one tends to show.

Preparing the ground

Choose a warm, sheltered, sunny site with fertile, free-drainingSoil that lets water pass through quickly rather than pooling, so roots aren't sitting in wet ground after rain. Full definition → soil; Florence fennel dislikes heavy clay and waterlogged ground just as much as it dislikes drying out, so the aim is soil that holds moisture evenly rather than swinging between wet and dry. Shelter matters too: an exposed, windy spot dries the ground out faster, which adds to the boltingA plant switching early into flowering and seed production, usually triggered by stress, after which leaves, roots or bulbs turn bitter or unusable. Full page → risk. Add well-rotted manure or garden compost in autumn, winter or early spring to build up that moisture-holding capacity ahead of sowing, or mulchA layer of material spread over the soil around plants to suppress weeds, retain moisture, and improve soil structure as it breaks down. Full definition → the surface for a no-digA growing method that avoids turning the soil over, building fertility instead by adding organic matter on the surface. Full definition → bed instead.

Sowing

This crop dislikes root disturbance, so sow either direct outdoors or singly in modulesA tray divided into small individual cells, each sown with its own seed or seedling, so each plant grows undisturbed roots until it's ready to plant out. Full definition →, never in a shared seedbed or tray.

Sow indoors from late spring, keeping seedlings in good light and watering regularly, ready to transplant outdoors from May. Don't sow too early: cold temperatures are one of the three main bolting triggers.

Direct sow outdoors in June or July, once the soil has properly warmed, in a shallow drillA shallow, straight groove made in prepared soil for sowing seed into, at a set depth so germination and rows are even. Full definition → 15mm deep, watered along the base first, with drills 30cm apart. Thin to 30cm apart for full-sized bulbs, taking care not to disturb the roots of the plants left behind, or 10-15cm if you want to harvest as mini veg at around 5cm wide, which takes roughly six weeks.

Planting

Transplant module-raised seedlings outdoors from May, once the last frost has passed and plants are hardened offGradually getting young plants raised indoors used to outdoor conditions over 7–14 days before planting out, so cold, wind and direct sun don't shock or damage them. Full definition →. Handle the roots as little as possible, and set plants at the same depth they were previously growing. Space as for direct sowing: 30cm apart for full bulbs, or 10-15cm for mini veg, and protect young plants from slugs and snails straight away.

In containers, use a pot at least 40cm wide for up to three mature plants, or space plants 10-15cm apart for baby veg. Containers dry out fast, which is a bolting risk in itself, so check them more often than you would ground-grown plants.

Varieties

Dragon and Rondo both carry the RHS Award of Garden Merit, a UK-wide award rather than a Scottish one. Zefa Fino has no award.

Gardener's World also names Sirio, Perfection, Cantino, Colossal and Amigo, and describes Amigo as an RHS AGMThe RHS's Award of Garden Merit: a UK-wide trials award for reliable performance, not a Scotland-specific recommendation. Full definition → variety. The RHS fennel guide doesn't list Amigo.

Also worth considering

Best Florence Fennel Varieties for Scotland → compares all named florence fennel varieties head-to-head, with the practical detail that doesn't fit in a summary card.

Care

Keep the soil or compost consistently moist: this is the single most important thing you can do for this crop, since dry conditions are a direct bolting trigger, not just a stress that slows growth. Water early in the morning where you can, ideally with collected rainwater. Mulch once plants are growing well, to hold moisture and suppress weeds. A high-potash feed every couple of weeks (Gardener's World) gives plants a boost. Weed by hand close to the plants rather than hoeing, so you don't damage the developing bulb, and keep the ground clear generally, since dense weeds also give slugs and snails somewhere to hide.

Once the stem bases start to swell, mound soil around them to blanch the bulb. It isn't always necessary, so treat it as an extra if you have the time.

Harvesting

Ready in late summer and autumn, depending on sowing time, roughly 14 weeks after sowing. Harvest once the bulb reaches 10-15cm across, though it can be cut from 5cm upwards if you'd rather take it smaller. Harvest before the bulb starts to elongate and send up a flower stem, after which it may turn woody. Either dig up the whole plant, or cut just below the swollen bulb with a sharp knife, leaving the base and roots in the ground: left in place, they may send up small leafy shoots for salads, though a second bulb won't follow.

Common problems

• Bolting is this crop's dominant problem: cold, disturbed roots and dry soil are the three triggers, and any one of them can undo the bulb.
• Slugs and snails target seedlings and young plants.

Common questions

Sources