Plant lists

Wonderful plants varying in form, texture and colour, TBG ON

The vegetation is a big opportunity to maximize the co-benefits of biodiversity and amenity. Planting plans can be formalized or naturalized to suit the surrounding style. In addition to aesthetic qualities, plants have specific functions in several LID practices. These include promotion of infiltration, treatment of pollutants and stabilization of soil. When selecting plants for an LID practice, aim for species with high functionality, survivability, suitability and availability. Landscape professionals should use these lists as guides, taking into consideration the appropriate planting zone, the size of the planting area versus size of the plant at maturity, tolerances to drought or periodic inundation, maintenance requirements and adaptability.

• To help you select appropriate plants for your site, we've developed tables to indicate the suitability for use in LID features.
• For resilient and robust planting, native species which can tolerate periods of drought and periodic inundation are recommended.
• Woody and evergreen plants should not be planted in any areas of the bioretention cell to be used as snow storage.
• Dense shrubby plants should be avoided in locations where the accumulation of trash is anticipated as a maintenance problem, or where their growth can hinder maintenance and inspection of inlets or other structures.
• Trees should not be planted directly over underdrains, and may be better sited at the perimeter of bioretention cells.
• While it is not always necessary to use an entirely native planting palette, invasive plants are inappropriate for LID practices.

Plant Selection

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Select trees Select shrubs Select perennials Select climbing plants Select tall grasses Select plants for green roofs Select plants for wetlands

Plant Characteristics

Soil moisture

Plant species are adapted to specific levels of moisture to achieve establishment and sustained growth. Soil moisture has been characterized by three categories: dry (1), moist (2) and wet (3). Some plants can tolerate a wide range of moisture regimes, whereas others perform optimally in a more narrow range of soil moisture conditions. Species ranked with a dash between two numbers can tolerate a range of conditions.

Shade tolerance

Plant species react differently to varying levels of sunlight and shade. Plant adaptations to these parameters are referred to in terms of degree of exposure. Most of the LID practices will be installed in newly developed areas, thereby providing exposure to full sun, meaning at least 6 full hours of direct sunlight for plantings. As trees develop over several years, or if an LID practice is installed in an area where there are existing trees or buildings providing partial shade, plants adapted to 3 to 6 hours of sunlight exposure should be used. Plants tolerant of full shade require less than 3 hours of direct sunlight each day. However, some shade-adapted species come into leaf early in the growing season in order to take advantage of full sunlight before tree leaves emerge and create shade.

Our tables indicate whether the species in question is tolerant of shade at all. For more information, consult the sources listed below.

Drought tolerance

These categories represent broad generalisations regarding drought tolerance.

Salt tolerance

The low, medium and high categories indicate the tolerance of plant species to salt exposure and/or uptake. Plant species with low salt tolerance should not be used in any LID practice receiving runoff from salted roads and parking lots. Species with medium salt tolerance can be utilised in LID practices that will be receiving road runoff but should not be in the line of salt spray or be receiving the bulk of the runoff. Species with high salt tolerance should be planted in LID practices that receive road or parking lot runoff that routinely contains road salt. Few plants are truly halophytic or “salt-loving”. In most cases, elevated salt levels are temporary and precipitation quickly dilutes and removes salt from the soil profile. The plant lists below include recommended species for LID practices likely to receive road or parking lot runoff.

Compaction and pollution tolerance

Development nearly always causes compaction of on-site soil, and bioretention facilities in road-right-of-ways should be pollution tolerant.

STEP stars

These are species which have demonstrated good performance in projects designed, installed and monitored by the Sustainable Technologies Evaluation Program.

Advanced plant selection criteria

Plant characteristic	Potential benefit to LID performance
Plant mass	Higher biomass consumes more nutrients (decreases nutrient discharge from bioretention) and increases transpiration rate.
Growth rate	Higher growth rate consumes more nutrients, particularly in combination with root characteristics as below.
Root lipid content	Higher root lipids have been associated with increased plant uptake of organic contaminants such as polyaromatic hydrocarbons (PAHs)
Root length	Longer roots are associated with plants consuming more nutrients, although roots which reach the bottom to the media may contribute nutrient...
Root mass and thickness	Larger overall root mass and many dense fine roots are associated with increased nutrient uptake by plants. Thicker roots help to preserve hydraulic conductivity of the media.
High-nutrient tolerance	Plants adapted to high nutrient environments are likely to uptake nutrients at a higher rate.

See Also

• Planting design
• Bioswales
• Rain gardens
• Materials
• Bioretention
• Green roofs
• Wetlands

External resources

Organization	Coverage	Types of Material	Website
Watersheds Canada	Canada / Ontario	Native Grasses, Ferns, Shrubs, Trees, Vines	https://watersheds.ca/plant-database/
Columbia University, University of Maryland, Smithsonian Institute1	North eastern USA and Canada	Native and non-native trees and shrubs	http://leafsnap.com/species/
North American Native Plant Society	N. America	Native Grasses, Ferns, Herbaceous, Shrubs, Trees, Vines	https://nanps.org/
Louisiana State University	USA	Grasses, Ferns, Herbaceous, Shrubs, Trees, Vines, Ornamental	http://onlineplantguide.com/Index.aspx
United States Department of Agriculture	N. America	Grasses, Ferns, Herbaceous, Shrubs, Trees, Vines, Ornamental	https://plants.usda.gov/java/

1. Leafsnap is an on-line field guide, available as a free mobile app that uses visual recognition software to help identify tree species from photos of their leaves, flowers and fruits.

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Low Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting.

A shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation.

Typically non-native plants that out-compete native species. These species lack natural predators, grow aggressively and reproduce rapidly and can be problematic in the natural environment.

The portion of water precipitated onto a catchment area, which then flows as surface discharge from the catchment area past a specified point.

Water from rain, snow melt, or irrigation that flows over the land surface.

Any form of rain or snow.

Sustainable Technologies Evaluation Program

A parameter that describes the capability of a medium to transmit water.

A shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation.

Refers to the conditions in which an organism lives and survives or the conditions in which an organism resides. These conditions can be described as aspects of a “physical”, “social” or an “economic” environment, depending on the perspective perceived by the observer.