There are many threats to Canada’s natural spaces, including climate change and irresponsible development. However, it is important to also to pay attention to how invasive plants are threatening our ecosystem.   

Invasive plants are those that, when introduced to an area they are not native to, spread aggressively and cause ecological harm.  

It was estimated in 2010 that invasive plants cost the Canadian agricultural industry $2.2 billion per year. Invasive plants also threaten native species and disrupt habitats. Native plants are vital to stable food production and a healthy environment as they support insects that pollinate crops and are a food source for several other creatures in the food web.   

Some invasive plants also impact their environment or humans in more unique ways. Some, like Giant Hogweed, can damage the skin of those who touch it. The roots of garlic mustard produce chemicals that can change soil chemistry, it unsuitable for other plants to grow there.  

The Grand River Conservation Authority (GRCA)  manages the water and other natural resources of the Grand River watershed. They own approximately 20,000 hectares of land and work to restore the land and maintain natural heritage.   

One of the GRCA’s responsibilities is monitoring and managing invasive species. Some species they have recently seen appearing on GRCA land are Phragmites and Dog-Strangling Vine.   

“You see these big areas kind of fully dominated by this vine that grows up to about a meter or two high but forms very dense patches and outcompetes native vegetation and ruins the habitat for all the creatures that are using it,” Ron Wu Winter, supervisor of natural heritage at GRCA, said.  

As it is so difficult to remove invasive plants once they have entered a natural space, this is a scenario where prevention is preferred to cure. The GRCA tries to address invasive species when their numbers are still relatively low or in an area where they may impact rare or endangered species.   

“Purple Loosestrife was a very popular ornamental plant decades ago, and then it escaped into the wild, into our wetlands, and when it became a problem, it was too late,” Karen Sciuk, president of Master Gardeners of Ontario, said.   

Master Gardeners of Ontario is an organization that aims to educate the public about gardening. They have recently started to focus on combating invasive plants and encouraging the growth of native species. Due to the amount of interest the master gardeners were seeing about invasive plants, they formed the Canadian Coalition for Invasive Plant Regulation (CCIPR) to address the lack of unified legislation to combat invasive plants in Canada.  

   Some of their recommendations include restricting the sale of invasive plants and the creation of a database to identify and rate invasive species. Individuals are also encouraged to ensure the plants they introduce to their property are not invasive and to edit out those that are. Those who would like to address the issue on a regulatory level are encouraged to write to their federal and provincial representatives.   

“A lot of things, I find, are grassroots, just by spreading the word. If you find out that periwinkle and English ivy and Lily of the Valley are [invasive], then maybe you start editing them out of your garden, one foot at a time,” Scuik said.  

It is also important to try to prevent invasive plants from entering green spaces. Residents should avoid dumping yard waste in natural areas and should check their boots or bike tires before they go hiking. Diseases such as Dutch elm disease have been transferred through firewood, so residents are encouraged not to transport firewood long distances.  

Planting native plants that support local insects and wildlife on one’s property is another way to mitigate some of the impacts of invasive plants.   

“My backyard was a blank slate. It’s a new house in an old farmer’s field. I’ve got trees and shrubs, lots of natives. I have orioles and grosbeaks and flocks of goldfinches. I have birds nesting, and all the spiders that used to hang out on my window are gone now because the birds are eating them all. It’s amazing,” Scuik said.    

“In eight years, my backyard has transformed, and I’ve got this ecosystem happening. And I just planted a few plants. That’s amazing. Everyone can do that,” she said.   

  The Ontario Invasive Plants Council has a list of invasive plants and provides materials on alternatives to grow instead of invasive species.