Garlic Mustard
Alliaria petiolata
A biennial woodland-edge weed that smells of garlic when crushed. It grows as a low rosette in its first year and sends up a tall flowering stem with small white flowers in its second spring.
Garlic mustard in flower — tall stems with small white flowers; smells of garlic.
Image source: Ontario weed-identification reference (OMAFRA / Ontario CropIPM)
At a glance
- Key clue
- Garlic smell; white four-petal flowers; scalloped leaves
- Best months
- April to June, when the white flowers are open on second-year plants
- Often found
- Backyard, Garden bed, Ravine edge, Fence line
- Easiest to remove
- Spring (hand-pull)
Why it's prohibited
Garlic mustard spreads quickly along woodland edges and gardens, releasing chemicals into the soil that suppress native plants and tree seedlings. A few plants can become a carpet within a couple of years.
Main identification features
- Garlic or onion smell when the leaves or stems are crushed
- First-year plants: low rosette of round, kidney-shaped, scalloped leaves
- Second-year plants: tall stem (0.3–1 m) with triangular, toothed leaves
- Small white flowers with four petals in spring
- Thin, upright seed pods that follow the flowers
Similar plants & look-alikes
- Violets — Violets have similar heart-shaped leaves but no garlic smell and purple (not white four-petalled) flowers.
- Ground ivy (creeping Charlie) — Ground ivy creeps along the ground with scalloped leaves but has a minty smell and purple flowers.
Month-by-month identification timeline
April to June, when the white flowers are open on second-year plants.
March–April (Early spring)
· 5–15 cmFirst-year rosettes of round scalloped leaves green up early; second-year plants begin to bolt upward.
Low rosettes of kidney-shaped leaves; garlic smell when crushed.
April–May (Late spring)
· 0.3–1 mSecond-year plants send up a tall stem topped with small white four-petalled flowers.
Clusters of small white four-petal flowers — easiest ID.
May–June (Late spring)
Flowers give way to thin, upright seed pods along the stem.
Slender upright seed pods forming.
July–August (Summer)
Second-year plants dry out and die after dropping seed; first-year rosettes persist low to the ground.
Dry tan stalks with pods; green rosettes remain below.
Fall–winter
First-year rosettes stay green low to the ground, ready to flower next spring.
Evergreen rosettes overwintering.
Growth-stage photo gallery
Photos of garlic mustard at different growth stages — note the visual features described under each one to identify it confidently.
A young seedling in spring, before the rosette fully forms.
A low rosette of round, kidney-shaped, scalloped leaves — stays green through fall and winter.
Second-year plants send up tall stems topped with small white flowers.
Small white 4-petalled flowers with long slender seed pods above triangular stem leaves.
Click any photo to enlarge. Image source: Ontario weed-identification reference (OMAFRA / Ontario CropIPM).
How to remove it safely
Safest resident-friendly approach
Hand-pull plants, including the slender taproot — the soil is usually soft and the whole plant comes up easily, especially after rain. Pull before the flowers set seed in spring. It's one of the easier prohibited plants for residents to manage.
Tools & protection
- Gloves
- A bag for pulled plants (especially if flowering)
Best time of year
Early to mid spring, before and during flowering, before seed pods ripen.
Monitoring
Revisit the patch each spring for at least 2–5 years, as seeds remain viable in the soil.
Prevent regrowth
Pull again each spring for several years to exhaust the seed bank; even small remaining plants can reseed.
What not to do
- Don't pull and leave flowering plants on the ground — they can still ripen seed
- Don't disturb the soil more than needed; bare soil invites new seedlings
Disposal
Bag flowering or seeding plants for the garbage so seeds aren't spread; do not compost plants that have flowered.
Safety cautions
- Low risk to handle — basic gloves are enough
- Bag flowering plants to avoid scattering seeds
When to get professional help
Rarely needs a professional; large woodland infestations may benefit from a coordinated community pull.
Bag and garbage any plants that have flowered or set seed; pre-flowering plants are lower risk but bagging is safest.
Sources
Report a prohibited plant
Found this plant growing on a property? Report it to the City through official Toronto 311.
Report through Toronto 311This page is provided for general educational and reference purposes only. Plant identification results are not a legal determination. Always confirm prohibited plant information using official City of Toronto resources. For hazardous species or large infestations, consider seeking professional advice.
Image credits & usage
Plant photographs are reproduced for non-commercial public education and identification reference only. Sources include Ontario weed-identification (OMAFRA / Ontario CropIPM) and invasive-species fact-sheet materials; all image rights remain with their respective owners. If you are a rights holder with a concern, please contact us through the Feedback page. Photos on this page: Ontario weed-identification reference (OMAFRA / Ontario CropIPM). Contact us.