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===Plant Selection===
===Plant Selection===
The nature of bioretention cells is to attenuate stormwater from rainfall events of varying intensities. For this reason, the vegetation used must be suitable for the varying moisture conditions and is often categorized into three zones related to the grading of the feature.
Low Zone (This area is frequently inundated during storm events, and is well-drained between rainfall
events.)
Mineral Meadow Marsh plant community
Grasses, Sedges, rushes, wildflowers, ferns and shrubs that have an ‘Obligate’ to ‘Facultative’ designation
Wetland ‘Obligate’ species that are flood tolerant as they will persist in average years and flourish in wetter years.
Plants that are likely to occur in wetlands or adjacent to wetlands.
Plants with dense root structure and /or vegetative cover are favoured for their ability to act as pollution filters and tendency to slow water velocity
Be advised these practices are not constructed wetlands and are designed to fully drain within 48 hours.
Mid Zone (This zone is inundated less frequently (2 – 100 year storm events) and has periodically high levels of moisture in the soil. The ecology of this zone is a transition from the Mineral Meadow Marsh/Beach-type community to an upland community.)
Plants able to survive in soils that are seasonally saturated, yet can also tolerate periodic drought.
Species include grasses and groundcovers, as well as low shrub species.
High Zone (The ecology of this zone is terrestrial due to its elevation in relation to the filter bed. The zone most closely resembles a Cultural Meadow or a Cultural Thicket community, depending on the mix of grasses, herbaceous material, shrubs and trees utilized.)
Plants should have deep roots for structure, be drought-tolerant and capable of withstanding occasional soil saturation.
Trees and large shrubs planted in this zone will aid in the infiltration and absorption of stormwater.
This area can be considered a transition area into other landscape or site areas.
A variety (min. five) species should be used to prevent a monoculture.
#Exposure to roadway or parking lot runoff
#Exposure to roadway or parking lot runoff
#*Select salt tolerant grasses, other herbaceous material and shrubs.
#*Select salt tolerant grasses, other herbaceous material and shrubs.