Groundcovers like goutweed, lily-of-the-valley and periwinkle often begin as living carpets — uniform, green and deceptively serene
Editor’s note: This is part five in a six-part series about invasive plants.Click on the following links for Part 1: Gardeners unknowingly fuelling invasive plant crisis, Part 2: The plants we love but shouldn’t trust, Part 3: Why invasive plants are everyone’s problem, and Part 4: GARDEN PATH: Silent swish of invasion: When ornamental grasses go rogue.
Creeper, creeper, in the shade —
Pretty face, but plans well-laid.
Planted once, but never stays…
Slips beneath and slowly strays.
What am I? (Answer: An invasive groundcover in disguise.)
They creep in quietly.
Sometimes we plant them ourselves — lured by the promises on the nursery tag: “Fast-spreading! No weeds! Maintenance-free!” Other times, they arrive on the wind, or in the droppings of songbirds.
Invasive groundcovers like goutweed, lily-of-the-valley, periwinkle, creeping Jenny, English ivy, pachysandra, euonymus, wintercreeper, and yellow archangel often begin as living carpets — uniform, green, and deceptively serene.
Beneath that benign façade, they suffocate spring ephemerals, choke young trees, and sever the fungal threads that sustain life in the soil. What seems orderly in the garden becomes ruinous in the wild as they lock out native wildflowers that insects and birds actually need to survive.
They are not “just plants.” They are ecological tumours, as entomologist Doug Tallamy puts it. And with tumours — even one is too many.
“But Mine Doesn’t Spread!”
Every gardener knows one: “Well, my periwinkle has never caused a problem!”
No, you may not see it spreading in your tidy mulch bed.
But check the ravine behind the subdivision, the park edge down the street, or roadside thickets — odds are, someone’s periwinkle patch has already jumped the fence.
When gardeners dump yard waste — even a single fragment — it can take hold in nearby forests or ditches. Periwinkle (Vinca minor) is especially harmful in forest understories, where it blankets the ground so densely that native plants can’t regenerate.
Most grazers avoid it due to its toxic leaves, and seeds are too small for birds to consume.
Even though I’m quite familiar with the dangers of periwinkle, I was stunned to see that Tree Canada labels periwinkle and other invasive plants as ‘tree killers” right alongside emerald ash borer, spongy moth, Dutch elm disease, and chestnut blight.
In fact, Tree Canada’s periwinkle page explains how dense mats of periwinkle prevent tree seedlings from establishing and can smother young saplings by shading them and depriving them of nutrients.
This invasive Periwinkle has replaced all native plants and threatens forest life. Photo: William Van Hemessen
My own battle
After a good soaking rain this fall — when the soil was soft and forgiving — I decided to confront my own patch of periwinkle.
I knelt at the edge of the glossy green mat and lifted one vine gently from the soil. Then I followed it. One stem turned into two. Two into five. Soon I was pulling long, wet ropes of vegetation, coiling them beside me like garden hose.
Periwinkle doesn’t just grow. It threads itself through the soil — rooting at every node, locking itself in like underground Velcro. What appears to be multiple plants on the surface is often one continuous organism expanding outward.
It was strangely satisfying — until I realized every broken fragment could resprout.
Goutweed (Aegopodium podagraria) — The Original “Plant-and-Regret”
Goutweed is the heartbreak story of many gardeners. It was introduced decades ago as a “fast-spreading, maintenance-free” groundcover — and nurseries still sell it today, despite its well-earned reputation as one of the most aggressive invaders in cultivated and natural spaces alike.
Trillium being consumed by Goutweed.
Goutweed creates dense carpets of vegetation that restrict the amount of sunlight available for native species.
Once planted, goutweed spreads through underground rhizomes — dense, rope-like roots that travel beneath the soil surface. Even a pea-sized fragment left behind can regenerate into a new colony. That’s why even meticulous gardeners struggle to control it.
Invasive plant removal is extremely difficult, especially once colonies are well-established.
It doesn’t stay pretty for long — variegated goutweed often reverts to solid green and spreads even faster into woodland edges.
If your infestation lies in full sun — solarization can help exhaust goutweed’s rhizomes. Cut plants low, water, cover with clear plastic for several weeks during the hottest months and let the sun do the work.
No sun? Use a dark tarp instead to block light.
More info: How to remove goutweed.
A Special Mention: Chameleon Plant (Houttuynia cordata)
It’s one of those plants that looks harmless in a pot — colourful leaves, low-growing, “great for damp corners!” — but underground it’s building a thick web of rope-like rhizomes that travel far beyond where you see foliage.
I found it sneaking into my asparagus bed this fall and started digging. I gave myself what I thought was a generous boundary — and was still pulling roots three feet down.
Every shovelful of soil had to be sifted by hand to remove fragments. And even then, I know I’ve probably missed bits that will resprout next spring. This won’t be a one-time removal — it’ll be multiple rounds of dig, wait, dig again.
Solarization rarely reaches roots this deep, so this one demands old-fashioned persistence: dig, sift, rest and dig again until you’ve starved it of light and strength.
Excavated Chameleon Plant rhizome network — extensive clonal spread via thick white rhizomes capable of regenerating from even small fragments.
Before You Dig: Smart Removal Strategies
Large removal projects aren’t just about tearing things out — they’re about planning what to save, what to sacrifice, and how to prevent re-infestation.
If you have desirable plants mixed in with invasives — say, hostas tangled with goutweed — decide whether it’s worth rescuing them before tackling the invader.
For full removal strategies, see Ontario’s Best Management Practices.
Many of these invasives were chosen for their usefulness — erosion control, fast cover, colourful blooms. Plenty of native groundcovers are just as tough — drought-tolerant, resilient and excellent for filling in tricky spots without taking over, like wild ginger, foamflower or barren strawberry.
You can explore a great list of native alternatives here.
Want to help on a bigger scale?
Three years ago, Ontario’s Auditor General has urged the province to ban the sale of invasive plants such as goutweed, periwinkle and English ivy, warning that continued sales fuel their spread into natural areas and drive up long-term costs.
If you’re frustrated that many of these plants are still legally sold, consider supporting the Canadian Coalition for Invasive Plant Regulation (CCIPR) — a volunteer-led group pushing for stronger rules on nursery sales and plant labelling across Canada.
(All photos by Monika Rekola, except where otherwise noted. Images identified as taken on the Rekola property are included for documentation of invasive species presence.)
Monika Rekola is a certified landscape designer and horticulturist, passionate about gardening, sustainable living and the great outdoors. Contact her at [email protected].Monika Rekola is a certified landscape designer and horticulturist, passionate about gardening, sustainable living and the great outdoors. Contact her at [email protected].
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