Such a pretty little plant, and such a thug.

Alliaria petiolata, otherwise known as garlic mustard, was imported from Europe many years ago for its culinary and medicinal properties. Since its arrival in the mid-1800s, however, it quickly naturalized and has succeeded in becoming highly invasive, particularly in forested areas where it dominates the understory. According to the USDA’s Natural Resources Conservation Service, there are only 12 states and three Canadian provinces in which garlic mustard has not been reported.

It’s a vigorous plant that grows to about 3 feet tall with a 1-foot spread, producing basal rosettes in the first year; these then bolt and flower in the second year. Young leaves are heart shaped, becoming more sharply triangular and toothed with maturity. Not surprisingly, a strong garlic odor is emitted when any part of the plant is crushed.

Second year plants produce tall stalks sporting small, four-petaled, white flowers in early spring. Fruits release seed in mid-summer, which is when the invasion begins. Deer ordinarily are not fond of garlic mustard and will bypass the plant for other treats, thus further reducing competition. In addition, it’s said that trampling hooves help to disturb the surrounding soil, making it just that much easier for seed to establish.

The best management method is to prevent seed production, which can be accomplished by removing plants prior to the flowering stage. It’s important to remove at least the upper half of the root in order to prevent a new stalk from forming. Hand control should be performed in spring and should be repeated for up to five or more years to assure that the established seed bank is eliminated. Chemical controls also may be applied.