By Sarah Brierley
It’s always a good time to strategize against invasive plants in the garden. When it comes to management, prevention, early detection, and rapid response are your best allies.
Among invasive plants, a few stand out for their relentless spread, resistance to eradication, and threats to human and environmental health.
The Town of Brome Lake website identifies four key invasive species of concern in our region:
- Japanese knotweed (Reynoutria japonica)
- Annual ragweed (Ambrosia artemisiifolia)
- Common reed (Phragmites australis)
- Giant hogweed (Heracleum mantegazzianum)
👉 See: lacbrome.ca/en/invasive-plants
The site also offers tips on how to control these problem plants.
To that list, I would add a fifth: goutweed (Aegopodium podagraria), also known as bishop’s weed or ground elder.
Goutweed: Deceptively Pretty, Aggressively Persistent
Don’t be fooled by goutweed’s delicate white umbel flowers or its usefulness as a quick groundcover. Whether green or variegated, this plant’s rapid growth and tangled rhizome network can choke out other plants and take over large areas of your garden. A single tiny rhizome fragment, no larger than your thumbnail, can sprout a new infestation.
Because rhizome fragments can remain viable for up to four years, I recommend non-invasive but radical methods of control:
- Blanket the area with four layers of cardboard, renewed over several years.
- Never rip it out by hand — this creates hundreds of new shoots from broken rhizomes.
- Never compost it, or toss it in nearby woods.
- If you dig it up, seal it in heavy-duty black plastic bags and solarize in full sun for at least three weeks until thoroughly cooked.
It’s worth noting that goutweed is banned for sale in Connecticut, Maine, Massachusetts, and Vermont — yet still sold in some Quebec nurseries.
Skip the Chemicals
I avoid herbicides like glyphosate (e.g., Roundup), which has been banned in Montreal since 2022.
Native Alternatives to Goutweed
If you’re seeking a low-maintenance, native groundcover that supports local pollinators and biodiversity, consider these species:
- Canada anemone (Anemonastrum canadense)
- Canada wild ginger (Asarum canadense)
- Golden alexanders (Zizia aurea)
- Heart-leaved foamflower (Tiarella cordifolia)
- Large-leaved aster (Eurybia macrophylla)
- Ostrich fern (Matteuccia struthiopteris)
- Pearly everlasting (Anaphalis margaritacea)
- Running strawberry-bush (Euonymus obovatus)
- Virginia waterleaf (Hydrophyllum virginianum)
- Wild strawberry (Fragaria virginiana)
- Zigzag goldenrod (Solidago flexicaulis)
Resources:
🔗 Québec Government Invasive Plant Info
🔗 Invasive Species Centre – Goutweed
About the Author:
Sarah Brierley is a graduate of Toronto Metropolitan University’s Landscape Design Program. She was Community Gardens Coordinator for Evergreen.ca in Toronto (specializing in native plants) and garden columnist for Toronto’s Annex Gleaner. She now resides in St-Étienne.
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