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Invasive Species Highlight: Garlic Mustard

As soon as the weather starts to warm up in the Midwest, garlic mustard begins to make its appearance throughout the landscape. Here are some tips on identifying and managing this invasive plant in your garden or woodlands.

Photo Credit: Katie Sickmann, Wild Rivers Conservancy


Garlic mustard is a flowering biennial plant that was originally introduced to North America from Europe in the 1800s to use in cooking, as the name implies. Since it was first identified in Long Island, New York, garlic mustard has spread rapidly throughout the Northeast and Midwest, and is now present in 37 states in the U.S., according to the USDA. This invader is often found in forested areas, but is also known to expand to roadsides and other disturbed natural areas. Garlic mustard spreads primarily through seed, and a single garlic mustard plant can produce up to 500 seeds.

Photo Credit: EDDMaps

Identification: In its first year of growth, garlic mustard only grows 2-4 inches above the ground in what is referred to as a basal rosette. In its second year of growth, however, the plant will shoot up to 3 feet tall and produce small, white flowers. Garlic mustard seeds are ridged and black, and are encased in narrow seed pods (siliques) that grow out from the stem. Another distinguishing characteristic is that, when crushed, garlic mustard leaves smell like garlic.

Photo Credits (from left to right): University of Minnesota Extension, Minnesota Department of Agriculture, Minnesota Department of Natural Resources

How to Manage:

Like any invasive species, it is important to note that continuous annual maintenance is required in order to see the best results.

Manual Treatment: One common option for garlic mustard management is manually pulling up garlic mustard plants. When pulling garlic mustard, it is important to try to pull up the whole plant, including the roots. The best time to pull year one garlic mustard plants is in the fall, whereas the ideal time to pull year two garlic mustard is in early spring, before the plants have gone to seed. Be sure to properly bag and dispose of all plants, never compost.

Mechanical Treatment: Mowing or trimming garlic mustard plants is another management option. This management option should be done after the plants have flowered, but before they have gone to seed to avoid spreading.

Chemical Treatment: Chemical treatment is another option for management, although it may be quite costly depending on the size of the population. The best time to spray year one garlic mustard is in fall, before the plants have the chance to overwinter. The ideal time to spray year two garlic mustard is early spring after the plants have flowered, but before the plants have gone to seed. Be sure to read and follow all safety precautions when using herbicide.

Photo Credit: Minnesota Department of Natural Resources

Prevention Techniques:

The best way to prevent the spread of garlic mustard is to properly clean all gear and equipment that is worn or used in an area where garlic mustard is or might be present. Garlic mustard spreads by the distribution of their small seeds, which can easily find places to hide in the treads of your hiking boots or on the blade of a lawnmower. Therefore, use water and/or a stiff bristle brush to clean off all gear and equipment to prevent the spread. After all, garlic mustard seeds stay viable up to seven years after they are dropped.

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