How to Grow Florence Fennel
Foeniculum vulgare var. azoricum
When to Start
Sow indoors 4 weeks before last frost, or direct sow outdoors after frost risk has passed and soil reaches 10°C.
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Growth Stages
Approximate days from start
Care Essentials
- Balanced liquid feed fortnightly. Needs consistent moisture to prevent bolting.
- Very bolt-prone. Sow in mid-summer, not spring. Avoid any check in growth — keep well-watered.
Companion Planting
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Growing Conditions
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- Sow indoors
- —
- Transplant out
- —
- First harvest
- —
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Spacing & Planting
| Plant spacing | 25 cm |
| Row spacing | 35 cm |
| Sow depth | 0.5 cm |
| Mature height | 60 cm |
| Mature spread | 30 cm |
Sow/plant after last hard frosts; steady moisture prevents bolting.
Care Guide
- Feeding
- Balanced liquid feed fortnightly. Needs consistent moisture to prevent bolting.
- Watch for
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- Bolting (major issue)
- Aphids
- Slugs
Pests & Diseases
Pest Aphids
Identification: Clusters of small green insects on shoot tips and developing bulbs, causing distorted growth and sticky honeydew
- Blast off with a strong jet of water
- Spray with fatty acid-based insecticide (check harvest interval for edible crops)
- Encourage ladybirds, lacewings and hoverflies
- Avoid chemical sprays close to harvest on edible crops
Pest Slugs and Snails
Identification: Irregular holes in leaves and damage to the swelling bulb base; slime trails around plants
- Use beer traps or copper tape barriers
- Apply organic slug pellets (ferric phosphate)
- Encourage hedgehogs, frogs and ground beetles
- Ferric phosphate pellets are safe near edible crops
Pest Carrot Fly
Identification: Yellowing foliage and stunted growth; larvae tunnel into the bulb base causing brown scarring and rot
- Cover with fine mesh or fleece barriers at least 60 cm high
- Avoid thinning plants in the evening when flies are most active
- Companion plant with alliums to mask scent
- No chemical controls available for home gardeners on edible crops
Disease Rhizoctonia (Bottom Rot) Rhizoctonia solani
Symptoms: Brown, sunken lesions at the base of the bulb, often with reddish-brown discolouration spreading upwards
Treatment: Remove and destroy affected plants. Avoid replanting in the same spot
Prevention: Ensure good drainage, rotate crops, and avoid earthing up with contaminated soil
Disease Downy Mildew
Symptoms: Yellow patches on upper leaf surfaces with greyish-white fuzzy growth on the undersides
Treatment: Remove affected foliage. Improve air circulation around plants
Prevention: Space plants well, avoid overhead watering, and ensure good airflow between rows
Growing Conditions
| Min. soil temperature | 10°C |
| Germination temperature | 15–22°C |
| Base growth temperature | 6°C |
| Min. daylength to start | 10h |
| Photoperiod sensitivity | long day |
Frequently Asked Questions
- How far apart should I plant Florence Fennel?
- Plant Florence Fennel 25cm apart with 35cm between rows.
- When can I harvest Florence Fennel?
- Florence Fennel is ready to harvest approximately 65 days after transplanting.
- Is Florence Fennel frost hardy?
- Florence Fennel is classified as Half Hardy.
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