Mugwort, or Artemisia vulgaris, is an herbaceous perennial weed that readily returns after being cut down. This plant is highly persistent and establishes itself vigorously across North America due to its sophisticated underground network. Mugwort’s resilience stems from specialized underground stems, not a simple taproot structure, which makes eradication challenging. The plant’s ability to return depends entirely on these subterranean organs, which store energy and facilitate vegetative reproduction.
Understanding Mugwort’s Invasive Rhizomes
Mugwort aggressively colonizes areas using an extensive system of rhizomes, which are horizontal underground stems. These rhizomes, up to 1 centimeter thick, form a dense, shallow network typically found within the top 20 centimeters of the soil surface. This structure allows the plant to spread laterally, creating large patches that choke out other vegetation.
Mugwort is difficult to eliminate due to fragmentation. If the rhizomes are broken—such as by tilling, digging, or cultivation—each small piece can generate a new, separate plant. Fragments as small as 2 centimeters are capable of regenerating a new shoot and root system, multiplying the infestation with every disturbance. Attempting to pull established patches by hand is often ineffective because it leaves behind numerous viable rhizome fragments ready to sprout.
The rhizomes function as storage organs, accumulating carbohydrates produced by the foliage throughout the growing season. This stored energy enables the plant to survive winter and quickly push up new shoots the following spring, even if the above-ground growth is destroyed. Successful long-term control must focus on exhausting or destroying this extensive underground biomass rather than just removing the visible stems and leaves. Mugwort will continue to return as long as any viable rhizome material remains in the soil.
Non-Chemical Methods for Eradication
Eradicating mugwort without herbicides requires a multi-season commitment to physical and cultural control practices. Manually removing the plant is possible, but it demands exhaustive digging to ensure the removal of every piece of the shallow, branching rhizome system. If the area is tilled or dug, all soil and plant material must be carefully removed and disposed of, since any remaining fragment can regrow.
Smothering is an effective non-chemical technique that works by completely blocking sunlight, starving the rhizome network of energy. This method involves covering the infested area with heavy-duty landscape fabric, black plastic sheeting, or a combination of cardboard and deep mulch. For large patches, solarization—using clear plastic sheeting to trap solar heat and destroy the rhizomes—can also be employed. Solarization requires high temperatures and several weeks of undisturbed coverage.
Another strategy involves the consistent removal of above-ground growth to deplete the energy reserves in the rhizomes. Frequent cutting or mowing throughout the growing season, ideally before the plant reaches the flowering stage, prevents the leaves from photosynthesizing and replenishing stores. Mowing alone is unlikely to achieve eradication; studies show only an 18 to 20 percent reduction in rhizome biomass after two years. However, it is an important component when combined with other methods.
Effective Herbicide Strategies
For large or persistent mugwort infestations, systemic herbicides are often the most practical method for long-term control. Systemic products, such as those containing glyphosate, are absorbed by the leaves and travel down through the plant’s vascular system to the rhizomes, killing the entire organism. Selective herbicides, including formulations with active ingredients like triclopyr or clopyralid, are also effective options.
The timing of application is a determining factor for successful chemical control. The most effective window is late summer or early fall, typically from August to the first frost. During this period, mugwort actively translocates carbohydrates from the foliage down to its rhizomes in preparation for winter dormancy, carrying the herbicide directly to the underground storage system.
Mugwort leaves have dense, silvery-white hairs on the underside, which can make herbicide penetration difficult. Using a non-ionic surfactant, a product that helps the chemical spread and stick to the waxy leaf surface, significantly improves effectiveness. Multiple applications over two to three years are often necessary to achieve high levels of control.