The first thing you can do is learn about invasive plants and how to identify them. Remember, not all non-native plants are considered invasive. For example, dandelions may be a nuisance to some, but they don’t pose a significant threat to native plants in southern Ontario. Instead, invasive plants are defined as non-native plants that are introduced to an area where they have negative environmental, social or economic effects. Some of the impacts of invasive plants include:
- Out-competing native plants for space and resources
- Destroying habitats of native plants and wildlife
- Reducing biodiversity – as we’re seeing in many of our local ravines
Here are three common invasive plants that you may find in your yard and some tips on how to manage their spread.
Dog-strangling vine (Cynanchum rossicum)
Dog-strangling vine (DSV) is an invasive plant that was brought over from Europe, has become established in southern Ontario and continues to spread at startling rates. Despite its name, DSV doesn’t pose a threat to dogs, but can hurt native plants and wildlife. It grows in thick mats, climbing up trees and other plants and it has a dense root system (resembling a pack of instant ramen noodles), which can choke out native species.
Did you know that DSV is part of the milkweed family? As a result, it poses a huge threat to our native monarch butterfly population, as they solely rely on the native milkweed plant to lay their eggs. Some monarchs mistake DSV flowers as milkweed flowers, and when their larvae hatch, the offspring eventually die due to a lack of food. You can help manage the spread of DSV by removing them from the roots and disposing of them in the garbage (not the compost) for several consecutive seasons. Then, plant native species in its place, such as native milkweed (Asclepias syriaca)!
Left: dog-strangling vine (Cynanchum rossicum) ©2011 jon haves
Right: common milkweed (Asclepias syriaca) ©2016 Brenna Anstett
Common buckthorn (Rhamnus cathartica)
Buckthorn was introduced from Europe as an ornamental shrub, but has quickly spread throughout many parts of Canada, including southern Ontario. This shrub/small tree is harmful because it grows in dense thickets, outcompeting native plants and preventing forest regeneration. It is also quite harmful to our native bird population - it’s dark berries are laxatives and can make birds sick!
You can help protect southern Ontario’s biodiversity and bird population by managing the spread of buckthorn. Remove buckthorn by digging it up by the roots (or other methods) and replace it with native trees and shrubs. Hackberry (Celtis occidentalis) is an excellent option, as they provide berries throughout fall and winter, as well as nesting sites for birds. LEAF also offers a Songbird Shrub Bundle which includes native shrubs such as red osier dogwood (Cornus sericea) and common elderberry (Sambucus canadensis) that provide food and shelter for birds throughout the year. If you are hesitant about removing mature buckthorn, you can help control the spread by pulling out any new buckthorn sprouts in your yard.
Left: common buckthorn (Rhamnus cathartica) fruit ©2018 Rudolphous
Right: hackberry (Celtis occidentalis) fruit ©2016 Brenna Anstett
Garlic mustard (Alliaria petiolate)
Garlic mustard is an edible herb native to Europe that was brought to North America in the early 1800s. Its aggressive growth shades out native plants and species at risk, such as American ginseng (Panax quinquefolius). The roots also release chemicals into the soil, interfering with fungi that bring nutrients to the roots of other plants.
Removing invasive garlic mustard is a win-win – you are helping native plants and wildlife thrive, and you get free edible herbs (try out this garlic mustard pesto recipe). To remove garlic mustard, hand pull from the root, ideally before it goes to seed, and dispose of them in the garbage (not the compost). It’s best to continue removal through multiple seasons, as the seeds can remain viable in soils for 10-15 years. You can replace garlic mustard with other native plants and groundcover such as wild ginger (Asarum canadense) and wild strawberry (Fragaria virginiana) – both of which are also edible!
Left: garlic mustard (Alliaria petiolata) ©2017 Plant Image Library / CC License
Right: wild ginger (Asarum canadense) ©2016 Janet McKay
Now that you’ve learned a bit more about invasive plants and how to manage them, here are some additional actions you can take to help stop the spread in your community:
- Share your invasive plant knowledge with your neighbours and community. Managing the spread of invasive plants is a shared effort, so the more people that are aware, the better!
- Report sightings of invasive plants to Ontario’s Invasive Species Awareness Program or track their spread on the EDD Maps Ontario website.
- Volunteer in your community to help remove invasives and plant natives. Check out the City of Toronto’s Community Stewardship Program and keep an eye on LEAF’s latest stewardship events and volunteer opportunities.
- Continue learning! Check out LEAF’s Native Species for Backyard Biodiversity Factsheet for tips on managing invasive plants in your yard and the Ontario Invasive Plant Council’s Grow Me Instead guide for tips on which native plants to grow in place of invasives.
Looking to add native species to your yard? We offer over 25 native trees and over 20 native shrubs through our Backyard Tree Planting option. Apply today!
Doreen Malapitan is the Residential Planting Programs Assistant at LEAF.
LEAF offers a subsidized Backyard Tree Planting Program for private property. The program is supported by the City of Toronto, the Regional Municipality of York, the City of Markham, the Town of Newmarket, the Regional Municipality of Durham, the Town of Ajax, City of Oshawa, the City of Pickering, the Township of Scugog, the Town of Whitby, Ontario Power Generation, Ontario Trillium Foundation and GrandTrees/Canadian Trees For Life.
