Plants

fennel

Foeniculum vulgare Mill.

Family: Apiaceae · Genus: Foeniculum

sweet fennel

Placenta I Low No biomass production 🪓 Coppices after cutting

Perennial Mediterranean herb (1–2 m), feathery anise-scented leaves. Seeds used as seasoning and medicinal. Bulb of the sweet variety is a vegetable. Hosts ladybugs and parasitoid wasps — beneficial in vegetable gardens. Fits between tree rows as an aromatic in syntropic systems.

Götsch succession

Götsch stage: Placenta I
Ecological role: Pioneer
Primary stratum: Low
Strata: Low, Ground cover
Biomass class: No biomass production

Environment

Light requirement: Full sun
Water requirement: Moderate
Drought tolerance: Moderate
Waterlogging tolerance: Moderate
Soil pH range: 5.5–7.5
Preferred soil texture: Loamy
Hardiness zones: 7–11
Frost tolerance: -10.0 °C

Morphology

Mature height: 1–2 m
Recommended spacing: 0.4–0.6 m
Root system: Taproot
Root depth: Medium
Growth rate: Fast
Lifespan: 3–7 years
Productive lifespan: 5 years

Biomes & climate

Atlantic Forest Naturalized
Cerrado Suitable
Pampa Suitable

Köppen classes

Hot-summer Mediterranean (Csa) Suitable
Warm-summer Mediterranean (Csb) Suitable
Humid subtropical (Cfa) Suitable
Oceanic (Cfb) Suitable
Subtropical with dry winter (Cwa) Suitable
Subtropical highland (Cwb) Suitable

Where it fits in a guild

Fennel takes the Low stratum in the Placenta I phase of succession — in a guild it shares the line with species from the other strata, each harvesting light at its own height, in its own time.

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🪴 Cultivation

Prefers well-drained light-to-medium soil, pH 6.0–7.5, but tolerates acidic to alkaline soils. Deep taproot with many lateral roots — dislikes transplanting; direct-sow. Tolerant of drought, frost and semi-aridity (hardy to zone 5). Note: naturalizes readily and is regarded as invasive in several regions (California, Australia) — manage self-seeding.

✂️ Management & Pruning

Cut flowering stalks to prolong leaf production; resprouts from the crown after being cut back. In consortium, mowing the top growth before it self-seeds prevents excessive spread.

📅 Phenology

Flowering months: October, November, December, January, February

❓ Frequently asked questions

What spacing is recommended for fennel?

The recommended spacing for fennel is 0.4–0.6 m.

How tall does fennel grow?

At maturity, fennel reaches 1–2 m tall.

When does fennel flower?

Flowering of fennel occurs in October, November, December, January, February.

What stage and stratum does fennel occupy in a syntropic system?

In a syntropic system, fennel belongs to the placenta i stage, occupying the low stratum.

Functions

Aromatic Medicinal 🍯 Melliferous 🐝 Attracts pollinators

Propagation

Seed

Citations

pfaf.org (root_system, root_depth, ph_min, ph_max, drought_tolerance, waterlogging_tolerance, hardiness_zone_min, hardiness_zone_max, frost_tolerance_c, flowering_months, soil_texture_preference, cultivation_notes, pruning_notes)
www.nwcb.wa.gov (cultivation_notes, biomes)