Fennel Foeniculum vulgare
Fennel (Foeniculum vulgare) is a deciduous perennial herb in the Apiaceae family, native to Mediterranean. It grows 1.2–2 m (3.9–6.6 ft) tall and 40–80 cm (16–31 in) wide, wants full sun and low water, and is hardy to about -29 °C (-20 °F). Space plants about 50 cm (20 in) apart.
Plan Fennel in your garden →
Free. Draw your beds, then watch it grow through the year in 2D and 3D.
Fennel at a glance
| Type | Perennial herb, deciduous |
|---|---|
| Family | Apiaceae |
| Mature height | 1.2–2 m (3.9–6.6 ft) |
| Mature spread | 40–80 cm (16–31 in) |
| Spacing | 50 cm (20 in) centre to centre |
| Sun | Full sun, at least 6 h of direct sun a day |
| Water | Low; drought tolerance moderate, waterlogging tolerance none |
| Soil pH | 6–7.5 |
| Cold hardiness | About -29 °C (-20 °F) once established (roughly USDA zone 4) |
| Heat stress | Likely above about 32 °C (90 °F) |
| Flowering | from about July for 6–10 weeks (northern hemisphere; later in cold climates, earlier in warm ones) |
| Wind tolerance | Low |
| Pollinator value | High |
| Edible | Yes: leaves, seeds, stem bases, flowers |
| Native to | Mediterranean |
| Common in gardens of | 🇬🇧 United Kingdom, 🇫🇷 France, 🇺🇸 United States, 🇮🇹 Italy |
| Invasive in | Australia (environmental weed, several states), US (California and other states): check local rules before planting |
Is Fennel toxic?
- People: not known to be toxic
- Cats: not well documented
- Dogs: not well documented
Common culinary herb; not listed as toxic in ASPCA references.
If a child or pet may have eaten part of a plant, call a poison centre or vet straight away.
Companion planting: what to grow with Fennel
No well-documented helpful pairing. Group it with plants that like full sun and low water.
Keep apart or take care
- avoid With Wormwood: Absinthin and related compounds released by wormwood have been shown to inhibit the growth of fennel and several other herbs in classic allelopathy trials. Keep them well apart. Evidence C
- caution With Nightshades: Fennel is reported to suppress tomatoes, peppers and many other vegetables nearby; grow it in its own corner. Evidence C
- caution With Legumes (pea family): Fennel is reported to suppress beans and peas growing next to it. Evidence C
- caution With Coriander (cilantro): Fennel and coriander are reported to inhibit each other's seed set; keep them apart if you save seed. Evidence C
Allelopathy: Root and leaf exudates (e.g. anethole, fenchone) are reported to inhibit germination and growth of nearby garden plants. (within about 60 cm (24 in))
Questions about Fennel
- How far apart should I plant Fennel?
- About 50 cm (20 in) apart, centre to centre. A mature plant spreads 40–80 cm (16–31 in).
- Does Fennel need full sun?
- Full sun: at least 6 hours of direct sun a day.
- How much water does Fennel need?
- Low water. Drought tolerance is moderate and waterlogging tolerance none.
- How cold-hardy is Fennel?
- It tolerates about -29 °C (-20 °F) once established, roughly USDA zone 4.
- When does Fennel flower?
- From about July for 6–10 weeks (northern hemisphere; later in cold climates, earlier in warm ones).
- Is Fennel poisonous to cats and dogs?
- For cats it is not well documented; for dogs not well documented; for people not known to be toxic. Common culinary herb; not listed as toxic in ASPCA references.
- What grows well with Fennel?
- There is no well-documented companion pairing for Fennel. Group it with plants that like the same sun (full sun) and water (low).
Sources and evidence
Evidence grade B (B: extension service or peer-reviewed).
- RHS Plant Finder, Royal Horticultural Society
- University extension gardening guides (general), Various land-grant university extensions
- CABI Invasive Species Compendium, CABI
- EcoCrop crop environmental requirements, FAO
Notes and assumptions
- Herb or bronze fennel (not the Florence bulb form). Self-seeds aggressively; deadhead in areas where it is a weed. Keep away from dill to avoid cross-pollinated seed.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
Related plants
- Carrot Daucus carota subsp. sativus
- Parsley Petroselinum crispum
- Celery Apium graveolens
- Coriander (cilantro) Coriandrum sativum
- Dill Anethum graveolens
- Parsnip Pastinaca sativa
- Celeriac Apium graveolens var. rapaceum
- Florence fennel Foeniculum vulgare var. azoricum