Michigan's Worst Woodland Weed: Garlic Mustard

Michigan's Worst Woodland Weed

Garlic mustard, is a highly invasive plant that should be controlled by all means. Garlic mustard quickly spreads, crowding out native plant species, which endangers insect diversity. In many locations in the United States, garlic mustard has become such a problem that their weed control boards are requiring property owners to eradicate it.

How to recognize garlic mustard

Dark green scalloped leaves are followed by tall stem stopped by tiny white flowers. Crushed young leaves have a garlic or oniony smell.

Settlers who proclaimed its medicinal properties and use it in cooking introduced this European native in North America.

Garlic mustard is a biennial – meaning it completes its lifecycle in just two years. The first year it is a diminutive, even attractive little plant with clusters of 3-4 rounded leaves with scalloped edges. These first-year plants remain green throughout the summer season and into late fall, making it easy to spot in the dormant season.

At this time of year, second season garlic mustard plants grow robustly and will send up a flower stalk resulting in tiny white flower clusters that pollinate quickly becoming seeds within a few days after flowering begins. Flowering plants can reach 20-40 inches. Seeds mature and become viable in July and August when the plant dies.

How to control

Any control method selected must be repeated for several years until the residual seed from previous year’s plants has germinated. In my experience, small garlic mustard infestations can be controlled with a watchful eye and rigorous hand-pulling. Composting is not a good option as seeds can withstand the compost heating process and may not be destroyed. 

Mowing or cutting has not proven to be the best solution, but if you can cut the plants before the flower buds have opened this is the best option to avoid future seed production. Some states have treated severe infestations by spraying Glyphosate (KillZall) in October or early spring on the green plants. This technique will minimize the impact on non-target plant material that is dormant.

Why does garlic mustard have such a bad name?

It may not look ugly, but don't let it fool you! A single garlic mustard plant produces between 600 and 7,500 seeds, which can survive in the soil for up to five years.

These seeds mature and crowd out native woodland plants and ferns.

Pull these invaders out, being sure to get the roots.

Information from MSU Extension

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