NIMBY: Nature in My Back Yard – Aliens among us

Cooler nights and the changing angle of the sun signal the end of summer and although there’s plenty of growing season left in 2025, now is a good time to start thinking about next year’s gardens.

However, before we dive into the many issues surrounding sustainable gardening and native plants, we need to have an honest conversation about non-native plants and in particular, invasive plant species.

The definition of an invasive plant, according to the Ontario Invasive Plant Council, is “… a non-native plant whose introduction negatively impacts native biodiversity, the economy and/or society …. Second to habitat loss, invasive species have been identified … as the most significant threat to biodiversity.” (Grow Me Instead, Page 3, Ontario Invasive Plant Council)

By contrast, “(a) native species has existed in an area for millennia, and has evolved in the presence of native soils and climate, and in tandem with other native species of plants, animals, fungi and bacteria. … Native plants exist as part of naturally-forming communities and have important ecological roles to play.” (Grow Me Instead, Page. 4, Ontario Invasive Plant Council)



Periwinkle is a common garden escapee that forms a thick mat on the forest floor and inhibits growth of native plants; photos by Christine Roberts

An invasive species well-known to residents and visitors to the lakeshore is Phragmites Australis, a robust reed that out-competes native plants and has spread extensively through waterways, wetlands, roadside ditches and agricultural drainage conduits. Fast-growing with many ways to propagate, phragmites is very difficult to control.

Its dominance in the landscape is of great concern in many areas: reduction of bio-diversity impacts habitat and food sources for many species of animals and plants; the wall of reeds reduces recreational opportunities and enjoyment of property; dry stands of phragmites can be fire hazards and the hardy reed can even grow through asphalt.

Dr. Janice Gilbert, a leading expert in the control of phragmites, consulted with the Municipality of Kincardine and the local citizen conservation group, Kincardine Residents Against Phragmites (KRAP) to remove and manage the aggressive plant along the Kincardine shoreline more than eight years ago. Great progress was made but constant vigilance is necessary as evidenced in the Aug. 31, 2024, article by Gail Walden, “Phragmites proving to be resilient in the Kincardine area.” The article, found at: www.kincardinerecord.com/story.php?id=16980, also includes astonishing “before” photos of impenetrable reed walls and subsequent “after” images of tranquil coastal views.

Another local citizen conservation initiative is trying to control the spread of invasive plant species in Geddes Park in downtown Kincardine.

Kincardine invasive stewards Michele Gade and Andrew Harris have encouraged and worked alongside residents over the past four years, pulling garlic mustard in May and June. This year, they expanded their scope to include Himalayan balsam and will tackle European buckthorn in the fall. All three species are widespread in the trail system and threaten the bio-diversity of the parklands. Gade and Harris welcome inquiries and assistance from the community and can be reached at trimeg@hurontel.on.ca.

As a member of Huron Bruce Nature and a steward of an Ontario Nature Reserve, I was well aware of the environmental impacts of these plants and the difficulty of control as I had been involved in “pull parties” for many years.

However, I received a rude personal awakening, following a workshop on invasive plants provided by the Lake Huron Coastal Centre for the Ripley and District Horticultural Society and organized by yours truly, in September, 2017.

Through introduction to the Ontario Invasive Plant Council and their excellent publication, “Grow Me Instead: Beautiful Non-Invasive Plants for your Garden,” I was horrified to learn I harboured many potentially-harmful plant species on my property.

Traditional ornamental gardens are full of non-native plants; plants that have been introduced to an area for horticultural or agricultural reasons. A cursory list of common plants is a virtual world tour: Japanese maple, Norway maple, Asiatic lily, English ivy, Russian olive, Japanese barberry, Oriental bittersweet, European buckthorn, and the list goes on. Most non-native plants in our gardens are non-threatening to native bio-diversity but all of the aforementioned species are considered invasive in Ontario.



The hill at the entrance to Geddes Park in spring is covered with daylilies, an invasive garden escapee that crowds out native plants

When talking about invasive plants, one often hears, “But it’s not invasive in my yard.” This demonstrates a common misunderstanding of the spread of non-native plants.

Have you ever walked in a natural area and been surprised by the presence of goutweed, periwinkle or English ivy? These ground-covers are common garden escapees that form dense mats of vegetation that crowd out trilliums, trout lily, blood root and other beautiful native ephemerals.

Many introduced species spread quickly because they lack their native competition or insects that control their growth. When they escape gardens and enter the local eco-system, they out-compete and crowd out native plants that are necessary food sources for insects and animals. Several negatively affect soil chemistry through the release of toxins that inhibit growth of other plants. Some, like phragmites and daylilies, have dense root systems that crowd out other plants.

Still others produce fruit that can be eaten by birds or small animals with the seeds deposited a distance from the original plant.



 We jokingly call this situation “battle of the titans” and often wonder which invasive ground-cover will come out on top: periwinkle or lamium?

Another way non-native plants are spread is through dumping of yard waste, particularly during the fall clean-up. It might seem benign to dump excess leaves on the edge of a forest or along a road but that is often the vector for a new infestation.

Our first action after learning of our potential problem was to take an inventory of our gardens using the guide to identify offenders. We removed the most aggressive species first and pledged to remove the remainder over time. In the recent past, we had planted periwinkle in the space between our house and the neighbour, but thankfully, the plants weren’t well-established and therefore, easy to remove - environmental crisis averted!

We hadn’t yet made the transition to favouring native plants over non-native but we were at least on the continuum.

My advice to people considering a shift to habitat gardening: inventory your plants, remove the more invasive first and start small. If total removal is too daunting (say, a large patch of goutweed), be satisfied with controlling the spread and monitoring the edges for satellite plants.

A side benefit of removing invasive plants, apart from protecting the local eco-system, is the fact that you’ve just gained space to fill with native plants that will benefit the environment.

A final word on non-invasive non-natives: although many horticultural specimens are benign and do not harm local eco-systems, neither do they contribute. They may provide food, likely of substandard quality, but they do not provide shelter or act as host plants for insects to complete their lifecycles and therefore, do not contribute to the food chain.

Visit the website of the Ontario Invasive Plant Council, www.ontarioinvasiveplants.ca/, for information on invasive plants and management practices. Updated in 2020, the “Grow Me Instead Guide for Southern Ontario” promotes the use of native and non-invasive alternatives for diverse, wildlife-friendly gardens and is available as a free download under Resources.



Lily of the Valley appears adjacent to several beach paths in Blair’s Grove