Garlic Mustard (Alliaria petiolata (Bieb.) Cavara and Grande) Information
By Ronnie Dauber, Garden Guides Contributor Garlic Mustard belongs to the mustard family (Brassicaceae). It is a biennial plant with a two-year life cycle, and produces seeds abundantly, often banking up to five years supply in the soil. It is an extremely aggressive and overpoweringly fast spreader. It is found in forest type areas and disturbed habitats such as forest trails or where trees have been removed.
General CharacteristicsIn the first year, Garlic Mustard plants appear to be small, dark purple rosettes that are kidney-shaped leaves with scalloped edges growing on stocks close to the ground from half to two inches long. Each plant can produce up to 17,000 seeds per square yard in the fall of which only the seeds that were exposed to extreme winter cold will survive. They produce a distinct garlic or onion odor which lessens as the plant ages. In the second year the leaves become rough triangle-shaped and sharply toothed, approximately 1 to 3 inches long and wide, and bear the same garlic/onion odor. The plants each produce from 350 to 8000 seeds and grow approximately 3/4 inch a day, or 20 feet per year, and reach a height of between 3 and 4 feet. White flowers bloom continuously from April to June.
Growing ConditionsIt grows well in shaded areas including alongside forest edges and dark trails. It spreads rapidly in disturbed forest habitats and requires no maintenance to retain its aggressive nature.
Cultivation and CareThis weed spreads quickly and gains much territory without any fertilizer or soil maintenance. It does not require regular watering or care and is an extremely low maintenance grower.
Weed Control TechniquesKeeping the infested area cut or mowed will help to control the distribution of further seeds but it will not kill the plant. It is best to remove Garlic Mustard when it is first discovered in the beginning rosette stage by pulling the plant physically out of the ground before the seeds are dispersed, making sure that the entire root is removed. This still requires a follow-up with an herbicide to eradicate any traces of the plant. However, established Garlic Mustard weeds in areas with high infestation are extremely difficult to remove. These plants can be physically removed or mowed down in the early spring before further seeds are deposited, but it is crucial that this be followed up with continued applications of strong herbicide. (Care must be given to surrounding plants so as not to destroy them.) This must be repeated for at least five consecutive springs since there could be a five-year seed supply buried in the ground. In areas where it is allowed, burning the ground and then following up with herbicide is a more sure way of being rid of this weed; but in many areas this is not possible. Therefore, physical removal with a follow-up of herbicide for several years is the only possibility of removing this aggressive weed.