The City of Toronto maintains planted and naturalized areas through best management practices such as forest thinning, prescribed burns and controlling invasive plant species. Those practices create healthy forests that provide many environmental benefits. Learn how you can help and what to expect when forest management operations are happening in your area.
A prescribed burn is a deliberately set and carefully controlled fire. These burns are a part of the City’s long-term management plan to restore and protect rare Black Oak woodlands and savannahs in Toronto’s High Park, South Humber Park and Lambton Park.
Pollution, construction, erosion and other factors deteriorate our natural habitats, and invasive species take advantage of the disturbance to thrive. Invasive species compete with native plants for growing space and nutrients. Please keep in mind that invasive species management on public land is done by qualified Urban Forestry staff only.
You may need a permit to Injure or Remove a Tree.
|Plant Type||Method: Manual Control||Method: Chemical Control|
|Herbaceous Annual or Biennial
(Garlic mustard, Himalayan balsam, tall sweet white clover, burdock)
|hand pull or cut close to the base when flowering||only in extreme circumstances|
(Daylily, Dog-strangling vine, Japanese knotweed, goutweed, lily-of-the-valley, Miscanthus grasses, periwinkle, phragmites)
||apply herbicide using spray bottle or sponge:
(Norway maple, Manitoba maple, white mulbery, English ivy, Siberian elm, white poplar, common buckthorn, winged euonymus, non-native honeysuckles, Asiatic bitterwseet,)
||cut stems and apply herbicide to stem|
Cosmetic use of pesticides is prohibited unless authorized by a permit from the Ministry of Environment, Conservation and Parks.
Learn about invasive insect species control.
Pruning of City trees will be completed according to good arboricultural standards and only if it is deemed necessary by the City.
According to good arboricultural standards, pruning is performed to:
Tree pruning is not performed to:
Download the City’s tree pruning guidelines.
Tree thinning is a selective removal of trees and shrubs from a densely planted area so that the remaining trees will have better access to growing space, light, water and other nutrients.
During a tree thinning:
Sites may look different after tree thinning.
Succession is the natural process of replacement of one group of plants by another group of plants in an area over time. Species that are more tolerant to shade will naturally replace the species that are fast-growing and less shade tolerant.
Tree thinning mimics succession. In the City of Toronto, thinning will be implemented in the areas that were densely planted with a mix of sun and shade-loving trees. Short-lived, sun-loving trees such as poplars provided habitat for the growth of long-living, shade-loving trees such as oaks and maples.
Once the long-living species become well established, the short-living species are removed to reduce the competition for growing space and promote the growth of the shade-loving species.
The Ontario Ministry of Environment, Conservation and Parks Cosmetic Pesticide Ban limits the use of pesticides by homeowners for cosmetic uses. There are exceptions for forestry management, arboriculture, health and safety, and natural resource management. Application of pesticides under these exceptions will require the services of a licensed exterminator.
The City of Toronto uses herbicides under the natural resources management exception to manage larger areas infested by aggressive invasive species that can’t be managed manually.
The City of Toronto uses two Class 9 pesticides regulated by the Pesticides Act.
Roundup Weathermax is the primary herbicide used by the City. It is considered non-toxic.
Garlon RTU is used for species that don’t respond to Roundup Weathermax. It is particularly good for roots. This herbicide can also be used in colder weather. It has a low-toxicity.
Coloured dye is mixed with the herbicides to indicate where it has been used. City staff will post signs indicating the area that has been treated. Please follow the instructions on the signs until they have been removed.
Pesticide use is regulated. Any use of pesticides (including herbicides) is prohibited in the city of Toronto and homeowners shall focus on manual methods of invasive species management.
In 2021, the City of Toronto entered into an agreement with Forests Ontario to provide source-identified native trees and shrubs for the City’s natural area planting programs. This 10-year contract will supply native source-identified trees and shrubs through the Tree Seed Diversity Program to expand nursery capacity and secure increasing amounts of plant material. This long-term agreement will allow the establishment of the required services including seed collection sources, nursery infrastructure and growing time to produce 25,000 native trees and shrubs annually.
Forests Ontario is a leader in tree planting in the province of Ontario and has extensive experience and expertise to carry out the deliverables for the Tree Seed Diversity Program. They have established relationships with a wide group of partners/subcontractor required to support comprehensive planning, seed collection, storage, stock production and delivery.
Planting trees and shrubs grown from seeds, which have been collected from appropriate climatic regions, will improve genetic diversity and support an ecosystem that is more resilient to climate change impacts. This is an important goal of the Toronto Ravine Strategy, Strategic Forest Management Plan, Biodiversity Strategy and the Toronto Green Standard.
More information about the Tree Seed Diversity Program is available on the Forests Ontario website.