1 / 14

Alliaria petiolata

garlic mustard

Brassicaceae

Europe, western and central Asia, northwestern Africa

Attracts Pollinators Deer Resistant Fragrant (moderate)

SunPart Shade – Full Shade

WaterMedium

HardinessZones 3–8

Overview

Alliaria petiolata is a biennial herbaceous plant in the mustard family (Brassicaceae) reaching 12–48 inches (30–120 cm) tall. First-year plants form a low rosette of kidney-shaped, scallop-edged basal leaves 2–4 inches (5–10 cm) across. Second-year plants bolt to an upright, unbranched or sparsely branched flowering stem. Stem leaves are alternate, triangular to heart-shaped, 2–3 inches (5–8 cm) long, with coarsely toothed margins. All parts emit a garlic-like odor when crushed. Flowers are four-petaled, white, 0.25 inch (6 mm) across, borne in terminal racemes from April through June. Fruit is a narrow silique 1–2.5 inches (2.5–6 cm) long containing black seeds. Roots produce compounds that suppress mycorrhizal fungi in the soil, disrupting native plant root symbioses. Listed as an invasive species in most of the United States and Canada. Seed bank persists in the soil for 5–10 years, making eradication difficult once established. Plants are shade-tolerant and colonize forest understories, floodplains, and disturbed roadsides.

Native Range

Native to Europe, western and central Asia, and northwestern Africa. Occurs across a wide elevational range from sea level to approximately 5,000 feet (1,500 m), typically in shaded or semi-shaded habitats including woodland margins, hedgerows, and riverbanks.

Suggested Uses

Studied in invasive species management research and ecological restoration programs. Young leaves and roots have historical culinary use in European cuisine. Included in weed identification courses for land managers and forestry professionals.

How to Identify

Identified by kidney-shaped, scallop-margined basal rosette leaves in the first year and triangular, coarsely toothed stem leaves in the second year. Crushed foliage produces a distinct garlic odor, distinguishing it from similar-looking species such as Glechoma hederacea (ground ivy) and Viola spp. species. Four white petals per flower, each 0.25 inch (6 mm) wide, arranged in terminal racemes on second-year stems.

Appearance

Size & Dimensions

Height1' - 4'

Width/Spread6" - 1'6"

Colors

Flower Colors

white

Foliage Colors

green

Fall Foliage Colors

no change

Bloom Information

Bloom Period

~4 weeks

Spring

Flowers from April through June in USDA zones 3–8. Individual racemes bloom over 2–3 weeks, with total flowering extending 4–6 weeks as lateral stems develop. Flowers are self-fertile and also cross-pollinated by small bees and flies. Seed set begins within 2 weeks of pollination.

Detailed Descriptions

Foliage Description

Dark green, kidney-shaped to triangular with coarsely toothed margins; crushed foliage emits garlic odor

Growing Conditions

Sun Requirements

SunPartial Shade SunFull Shade

Requires 2-6 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 - 7.5(Neutral)

357912

Soil Types

loam clay silt

Drainagemoist

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

1-2 years

Care & Maintenance

Care Guide

Classified as a noxious invasive weed across most of North America; management focuses on removal rather than cultivation. First-year rosettes can be hand-pulled before the taproot thickens. Second-year plants are pulled most effectively before seed set in late spring. Pulling after flowering but before seed dispersal reduces the next generation but does not eliminate the seed bank. Seeds remain viable in soil for 5–10 years, requiring repeated annual removal. Mowing before seed maturity reduces seed production but does not kill established root crowns. Root fragments left in soil may resprout.

Pruning

No pruning applicable. Management involves removing entire plants including roots before seeds mature. Cutting stems at ground level after flowering but before seed drop reduces dispersal; however, cut stems with developing siliques may still ripen viable seed if left on site.