What hardiness zones is Foeniculum vulgare suitable for?

Foeniculum vulgare is suitable for USDA hardiness zones 4, 5, 6, 7, 8, 9, 10.

What are the sun requirements for Foeniculum vulgare?

Foeniculum vulgare requires Full Sun.

How much water does Foeniculum vulgare need?

Foeniculum vulgare has Low water needs.

Herbaceous

Foeniculum vulgare

Fennel

Apiaceae

Mediterranean region, southern Europe

At a Glance

TypePerennial

HabitUpright

FoliageDeciduous

Height36-72 inches (90-180 cm)

Width18-36 inches (45-90 cm)

Growing Zones

USDA Hardiness Zones

4 - 10

Zone 4

Zone 5

Zone 6

Zone 7

Zone 8

Zone 9

Zone 10

These zones indicate the coldest temperatures this plant can typically survive.

Frost Tolerancehardy

Key Features

Attracts Pollinators

Attracts Butterflies

Deer Resistant

Drought Tolerant

Fragrant (strong)

Maintenancehigh

Overview

Foeniculum vulgare is a tall, aromatic, herbaceous perennial in the carrot family (Apiaceae) reaching 36–72 inches (90–180 cm) tall with an 18–36 inch (45–90 cm) spread. Stems are erect, smooth, blue-green, hollow, and branching in the upper half. All parts emit a strong anise (licorice) scent when crushed. Leaves are very finely dissected into thread-like (filiform) segments 0.5–1.5 inches (1–4 cm) long, bright green to blue-green, alternate, with inflated sheathing bases. Flowers are small, yellow, borne in compound umbels 3–6 inches (8–15 cm) across, lacking both an involucre (bracts below the umbel) and an involucel (bracts below the umbellets). Fruit is a ribbed, aromatic mericarp 0.15–0.2 inch (4–5 mm) long. A single plant produces 5,000–50,000 seeds. The taproot is deep and fleshy, reaching 12–24 inches (30–60 cm). Wild fennel forms dense, monoculture stands along roadsides, coastal bluffs, and disturbed areas, particularly in Mediterranean-climate regions. Listed as a noxious weed in several western U.S. states. Larval host plant for the anise swallowtail butterfly (Papilio zelicaon).

Native Range

Native to the Mediterranean region and southern Europe, occurring in dry grasslands, rocky coastal slopes, and waste ground from sea level to approximately 3,500 feet (1,100 m). Widely cultivated as an herb, spice, and vegetable. Naturalized across western North America, particularly along the Pacific coast from British Columbia to California, and in the southeastern United States.

Suggested Uses

Used in weed identification training for Pacific coast land managers and in Apiaceae morphology courses. Larval host plant for the anise swallowtail butterfly (Papilio zelicaon) and a nectar source for beneficial insects including parasitic wasps. Cultivated forms are grown commercially for the bulbous leaf base (Florence fennel), the aromatic seeds (spice fennel), and the foliage (herb). Studied in invasion ecology of Mediterranean-climate grasslands.

How to Identify

Distinguished from Anethum graveolens (dill) by the perennial habit (versus annual), the larger overall size, and the thread-like leaf segments 0.5–1.5 inches (1–4 cm) long versus shorter in dill. Distinguished from other Apiaceae by the strong anise scent of all parts, the absence of involucral bracts below the umbel, and the yellow flowers. Distinguished from Conium maculatum (poison hemlock) by the anise scent (versus musty), the very finely filiform leaves (versus broader pinnate divisions), and the absence of purple stem blotches.

Appearance

Size & Dimensions

Height3' - 6'

Width/Spread1'6" - 3'

Colors

Flower Colors

yellow

Foliage Colors

green

Fall Foliage Colors

no change

Bloom Information

Bloom Period

~6 weeks

SummerFall

Flowers from June through September. Individual umbels bloom for 7–10 days. Compound umbels open sequentially from the terminal head downward over 4–6 weeks. In the Pacific Northwest, peak bloom occurs in July through August. Seeds mature by September through October. Pollinated by a wide range of insects including bees, flies, and parasitic wasps.

Detailed Descriptions

Flower Description

Yellow

Foliage Description

Bright green to blue-green, very finely dissected into thread-like (filiform) segments, with an anise scent when crushed

Growing Conditions

Sun Requirements

Full Sun

Requires 6-12 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.5 - 8.0(Neutral)

357912

Soil Types

loamclaysandsilt

Drainage

well drained

Water & Climate

Water Needs

Low

Frost Tolerance

hardy

Time to Maturity

1-2 years

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Listed as a noxious weed in several western states; management focuses on preventing seed production. Plants are dug or pulled; the deep, fleshy taproot is best extracted from moist soil. Cutting at ground level before seed set prevents reproduction but plants resprout from the root crown. Repeated cutting 3–4 times per growing season for 2–3 years depletes root reserves. Mowing roadside populations at the early bud stage prevents seed production. Dense stands shade out native vegetation and reduce plant diversity. The deep taproot and drought tolerance make fennel persistent on dry, infertile sites. Escaped cultivated fennel contributes seed to wild populations; deadheading garden fennel prevents self-seeding.

Pruning

No pruning applicable in a weed management context. Plants are cut at ground level before seed set. Cutting after the onset of flowering but before seed maturity prevents dispersal. Root crown resprouting requires repeated cutting over multiple seasons. In garden settings, removing spent flower heads prevents self-seeding.

Maintenance Level

high

⚠️ Toxicity Warning

Non-toxic

Planting Guide

Planting Methods & Timing

Planting Method

direct sow

Days to Maturity

80–115 days

Plant Spacing

12 inches