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The fast-spreading periwinkle turns your garden into a desert for wildlife. Luckily, there’s an alternative.
There’s nothing like having a yard full of flowers to greet you when you step out the door in the morning and when you return home. But not all flowers are created equal. Native plants provide habitat and food for a whole ecosystem of wildlife, from butterflies and native bees, to birds and mammals. Non-native plants, which may look the same to the untrained eye, take up space and resources but create a wildlife desert. Some non-native species are also invasive, which means that their introduction or spread negatively impacts native biodiversity, as well as the economy and society, including human health.
Invasive Plants in the Garden
The horticultural and nursery trades are one of the primary pathways for invasive species introductions. While many horticultural plants are harmless garden additions, some can escape cultivation into natural areas and negatively impact biological diversity. Unfortunately, many invasive plants are still available for sale through garden centres, nurseries, or online through mail-order, which contributes to the spread of invasive species over great distances. For this reason, it is important to educate yourself when purchasing plants from retailers, to ensure you are not unknowingly introducing an invasive plant species into your garden.
One common ground cover plant found in many gardens is periwinkle. It is, unfortunately, invasive.
Why Periwinkle Gets the Thumbs Down
Periwinkle can escape from gardens into natural areas where it negatively impacts the forest understory by:
- 👎🏼 Displacing native understory plants
- 👎🏼 Changing the soil microhabitat
- 👎🏼 Serving as a poor food source for wildlife species.
- 👎🏼 Plus, its leaves are toxic to grazers.
How it got here:
- Periwinkle species (Vinca spp.) are native to Eurasia and the Mediterranean, and were first introduced to North America as fast-growing, ornamental groundcovers in the 1700s.
- They are one of the top 10 bestselling groundcover plants in the United States, with over 30 cultivars available that differ in growth rate, flower, and foliage colour.
Why it’s such a good invader:
- It is able to form dense mats of vegetation quickly, spreads by belowground and aboveground runners, and can thrive in a wide range of soil and habitat types. It also has a longer growing season compared to native plants.
- Its popularity as a groundcover is based on its ease of care, dense growth in a short time period, and its ability to grow in replete areas where few other plants will grow. Periwinkle is characterized by glossy evergreen foliage and long-lasting blue-violet flowers.
- Periwinkle (both species Vinca minor and V. major) are still available for sale in garden centers and nurseries.
How to remove it:
Periwinkle can be removed by hand pulling, making sure to remove all stems, stolons, and root nodes. Loosen roots and soil first by using a rake to raise and loosen the stolons and roots. For well-established, dense mats that are too difficult to hand pull, plants can be dug. Consider using landscape fabric or cardboard to tarp small areas for at least a season after control to help reduce regrowth.
Why Wild Geranium Gets the Thumbs Up
Wild geranium (Geranium maculatum) is a native, non-invasive ground cover alternative to periwinkle:
- 👍🏼 It is drought-tolerant once established in gardens, and prefers well-drained medium-to-moist rich soils.
- 👍🏼 It forms loose clumps of basal, deeply-lobed leaves with attractive pink-purple flowers that bloom in the late spring or early summer.
- 👍🏼 The nectar and pollen of the flowers attract native solitary bees, bumblebees, and syrphid flies.
- 👍🏼 The seeds attract species of songbirds and eastern chipmunks.
Where to plant it:
Ground cover for shaded woodland gardens or areas in full sun or partial shade. Its native habitat includes deciduous forests, savannas, and meadows.
Where to buy it:
The North American Native Plant Society (NANPS) offers a list of commercial growers.
The Grow Me Instead (GMI) Guide
To help gardeners make informed decisions about the plants they are buying for their gardens, the Ontario Invasive Plant Council (OIPC) developed the Grow Me Instead (GMI) guide. The GMI guide is a practical and easy to use guide that informs gardeners about the invasive tendencies of common garden plants and suggests appropriate non-invasive alternatives. It provides tips for ecologically sound gardening and choosing plant species that will benefit local populations of insects and other wildlife.
The Ontario Grow Me Instead guide is available on the Ontario Invasive Plant Council (OIPC) website to download.
Want to read more about native species? Read about Toronto’s Seed Diversity Program to Replace Invasive Tree Species.
