Florence fennel
Foeniculum vulgare var. azoricum
Also known asBulb fennel · Finocchio · Sweet fennel · Florence fennel
Environment
The bounded range this crop tolerates.
Climate and zones
- USDA zones
- 5–10 (winter low around -29°C)
- Frost
- tolerates light frost
- Season
- cool (spring/fall)
Growing systems
Root mass: moderate.
Growing media
| Medium | pH effect | Retention | Bacterial surface |
|---|---|---|---|
| Soil-based mix (Potting soil) | varies | high | high |
| Coco coir (Coconut coir) | slightly acidic | high | moderate |
| Expanded clay pebbles (LECA) | neutral / inert | low | high |
Nutrient demand by stage
NPK ratios are relative weights. EC targets shift through the plant's life.
| Stage | N | P | K | EC (mS/cm) |
|---|---|---|---|---|
| seedling | 1 | 1 | 1 | 0.8 |
| vegetative | 2 | 1 | 3 | 2 |
Companion-growing notes
- Heavy uptake of potassium. Co-grown crops with the same demand will end up deficient even at "correct" EC.
- Releases root compounds that can inhibit other crops in a shared reservoir.
Aquaponics suitability
Compatible
Fish waste provides enough nitrogen for healthy growth. Supplemental potassium, calcium, and iron may still be needed depending on fish stocking density.
Care notes
A cool-season hydroponic crop requiring careful temperature management to prevent bolting before the bulb develops. Media bed or large container systems (the bulb forms at or above the media surface). EC 1.5-2.5 mS/cm. pH 6.0-7.0. Temperature: 12–22°C (critical: above 24°C, the plant bolts before forming a usable bulb, producing only a thin, fibrous base). Moderate light (DLI 14-20 mol/m2/day). From seed to bulb harvest: 70-90 days. Transplant seedlings carefully; fennel is sensitive to root disturbance and transplant shock can trigger bolting. Hill media around the developing bulb to blanch it white. Harvest when the bulb is 8–12 cm diameter and firm. Overmaturity causes fibrous texture and splitting as the flower stalk pushes through. The feathery fronds are harvestable as a herb throughout growth. Bolt-resistant varieties ('Orion', 'Perfection') perform better in systems with imperfect temperature control. A rewarding specialty crop for Mediterranean cooking enthusiasts. For commercial hydroponic growers, fresh fennel bulbs command $4-8/kg and occupy a specialty niche at markets and restaurants.