In the garden: Goutweed earns menace moniker

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The Ontario Invasive Plant Council describes goutweed (Aegopodium podagraria) as “one of the worst garden weeds in perennial gardens.” The City of Ottawa agrees: it is one of the 24 plants on its Invasive Species List, which recommends gardeners avoid planting goutweed near natural areas. There’s even a bylaw (No. 2003-498) that prohibits homeowners from planting it as an alternative to grass on city-owned rights of way. Several U.S. states have restricted the use of goutweed or banned it altogether. And on June 4, 2026, Quebec implemented a new law restricting or prohibiting the sale or distribution of 31 invasive plants, including goutweed. 

If you have this groundcover on your property, you understand these decisions completely.  

Goutweed is native to Asia and Europe, where it has long been cultivated to provide a remedy for gout and rheumatism. Settlers introduced it to North America in the mid-1800s as an ornamental plant.  

There are two types: one with solid green leaves and a variegated type (A. podagraria ‘Variegata’) with creamy white edges surrounding blue-green centres. White, umbrella-shaped flowers stand above the leaves from June to August.  

Goutweed is a low maintenance plant, adaptable to various soil and light conditions, and can cover the ground quickly. These characteristics made it an appealing ornamental for many decades. However, these very characteristics also make goutweed a menace. In urban landscapes, it spreads aggressively without regard to property lines, fences, or other plants in the garden. And should it escape from a garden adjacent to a meadow or woodland, it chokes out other native groundcovers indiscriminately. 

Even more unfortunate is the fact that goutweed has a number of aliases, which can make it easy for gardeners to purchase it unknowingly. Goutweed is sold as ground elder, English masterwort, bishop’s weed, and the very inviting snow-on-the-mountain. 

To meet consumer demand, some vendors continue to sell the plant. There is currently no legal incentive for Ontario vendors to stop doing so; goutweed is not included in either the Ontario Weed Control Act (1990) or the Ontario Invasive Species Act (2015 and 2024.) So, unless sellers voluntarily remove goutweed from their stores, or recommend alternatives to buyers, the plant will continue to be available. 

Meanwhile, goutweed is notoriously difficult to eradicate once established. It uses several survival strategies. It grows quickly, so each plant can expand 60 centimetres to 1 metre in a single season. Its roots (rhizomes) also spread rapidly and can reach a depth of several metres. The rhizomes break easily, and each fragment will grow another plant. Those fragments can live in the soil for up to four years.  

Several control methods known to gardeners are ineffective with goutweed. Hand pulling cannot get the entire rhizome network; roots will break, remain in the soil and sprout new plants. Cultivating by hand or machine will just chop the roots, often into pieces too small to notice, and result in an even worse resurgence.  

If you have a small patch, you can dig deeply (60 centimetres), remove the plants and put them in the garbage. Then – most importantly – sift the soil through a screen to remove any remaining roots. Alternatively, cut or mow the plants down to about 2.5 cm to weaken and eventually kill them. Expect to have to repeat either of these methods several times over a couple of years. 

For larger infestations, you will need to either smother or solarize the plants. To smother, cover the plants when they emerge in spring with a heavy black plastic tarp. (Or use several thick layers of cardboard topped with 30 centimetres of mulch.) Ensure the covering extends about one metre beyond the edge of the goutweed patch so the roots don’t creep out past the cover. Leave the cover in place for an entire year. The second spring, check the progress. Repeat if necessary. 

Solarizing should only be used in sunny areas where there are no large trees or shrubs. In spring when foliage emerges, water the soil deeply until it is wet. Cover the area with clear plastic to allow the sun to cook the plants. Bury the plastic edges in the soil to trap the heat. Leave the cover on during the entire summer. Check the progress and re-solarize if necessary. 

Be cautious when saving any desired plant from an area where goutweed is growing. Dig it, remove any rhizomes you see, then pot the plant and quarantine it for three months before replanting in the garden. 

Far beyond posing significant difficulties for gardeners, goutweed continues to threaten many of Ontario’s natural woodlands and meadows. In the absence of legislation, growers, sellers and buyers need to educate each other about this plant.  

(Lee Ann Smith volunteers with Master Gardeners of Ottawa-Carleton.)