The key to controlling garlic mustard (Alliaria petiolata) is to attack infestations early this spring before the plants have a chance to go to seed. Garlic mustard is a priority for control because it quickly invades shaded woodland habitats and alters soil chemistry. That makes the woods less hospitable to our native plants and dramatically decreases forage for native animals.
Garlic mustard is a biennial plant. In its first year it appears as a low growing rosette with kidney-shaped scalloped leaves that smell like garlic if you crush them. In our climate, many of these rosettes overwinter and as soon as the weather begins to warm up they grow very rapidly. In the second year, in early spring, the plants grow tall (12-48 inches) and feature white flowers with four-petals each that quickly transform into seed pods.
The best time to pull garlic mustard is when it has just started flowering, before any seeds have been made. Pulling works best if the soil is moist such as after rainfall. Be sure to pull at the base of the plant and to get all the roots out, because roots left in the ground can re-sprout and form new plants. It is best to put all flowering plants in bags and dispose of with your trash, because plants that are pulled and laid on the soil may set seed. Do not place garlic mustard plants in compost or any other vegetative material, where the seeds can remain alive.
Prevention is crucial! Clean your boots, bike tires, pets and car tires after traveling through infested patches. Try to be strategic about not spreading the infestation on your own property by working from the outside of the infestation in and then cleaning your boots with a brush after leaving the infested areas.