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Garlic mustard

Quick facts

Garlic mustard is an invasive species. Garlic mustard is on the Restricted weed list. It is illegal to import, sell or transport propagating parts.

  • Garlic mustard is an herbaceous plant found in the understory of high-quality woodlands, upland and floodplain forests and disturbed areas.
  • It inhibits beneficial fungi associated with native plants, causing a decline in herbaceous vegetation within five to seven years.

Garlic mustard should be reported. Learn how to report invasive species in Minnesota. 

Garlic mustard (Alliaria petiolata) is an invasive biennial herbaceous plant. Garlic mustard is a restricted noxious weed, meaning it cannot be transported, introduced, or sold in Minnesota. 

One challenging aspect of garlic mustard, aside from how easily it spreads, is its effects on other plants. Studies suggest the plant is allelopathic, which means it releases chemicals that can hurt the growth of its neighbors. 

Over time, a large patch of garlic mustard can severely damage native plant populations that would otherwise thrive in the area. It has been shown to cause harm to native plants including trilliums, trout lily, red maple and sugar maple. 

Garlic mustard also thrives with disturbance, making places that are already impacted by earthworm damage and deer browse especially susceptible to invasion and difficult to control.

Patch of first-year garlic mustard rosettes near a tree.
Patch of first-year garlic mustard rosettes
Garlic mustard leaves with small flower bud.
Mature garlic mustard leaves
Garlic mustard plant with small white flowers.
Garlic mustard flower

How to identify garlic mustard

  • It forms a rosette in the first year, one to six inches tall, and grows to one to four feet high in its second and flowering year.
  • Often the only plant of this height blooming white in wooded environments in May.

Stem

  • Weak single stems.

    Leaves

    • Dark green leaves are round with a scalloped edge.
    • Second year plants have alternate leaves. Leaves and stems smell like onion or garlic when crushed.
    • Leaves remain green throughout the winter.

    Flowers

    • Numerous small, white flowers with four separate petals are present on second year plants.

    Seeds

    • Slender capsules, one to two and one half inches long, containing a single row of oblong black seeds.
    • Seeds mature in July or August and are viable in the soil for five years.
    • Spread along wildlife trails.

    Roots

    • White, slender taproot, S-shaped at the top.
    • If pulling plant, need to remove the root.

    Common look-alikes

    Because garlic mustard is a biennial plant, the first year of its life is spent as a rosette of leaves low on the forest floor. It is often confused with either wild ginger (Asarum spp), creeping Charlie (Glechoma hederacea), or violets (Viola spp) due to its kidney bean-shaped leaves. Luckily, garlic mustard also tends to be true to its name, as crushing the leaves can give off a mustardy, garlic odor.

    Its first-year leaf edges are scalloped with blunt, shallow teeth. Second-year leaves look more triangular further up the stem, but they will still have scalloped edges.

    Unlike creeping Charlie and wild ginger, garlic mustard does not spread vegetatively. If you pull garlic mustard plants you will not find runners or rhizomes, but a single crown with an S-shaped root attached.

    Reporting

    Garlic mustard populations can be patchy and very localized. It is important to report any plants you find in order to help control spread. If you find garlic mustard, report it using either the Great Lakes Early Detection Network smartphone app (available free for iOS and Android) or the EDDMapS Midwest website.

    Management

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    Management strategies

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    Authors: Angela Gupta, Amy Rager, Megan M. Weber, Extension educators

    Reviewed in 2021

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