The layout of plant material can be a flexible process; however, two basic guidelines should apply to all bioretention areas.

First, woody plant material should not be placed directly within the entrance-inflow path. Besides possibly concentrating flows, trees and shrubs can be damaged as a result of the flow causing soil to be washed away from the root ball.

Second, keep in mind that all areas of the facility will not be subjected to the same depth of ponding and saturation. The gentle bowl shaped configuration of the facility lends itself to differing zones of saturation. This provides an opportunity to utilize plants that cannot tolerate saturated conditions along the outside perimeter of the facility. This can be especially useful when visually linking a facility into an adjacent area landscaped with a formal theme.

Often designers will find that the environmental factors such as sun, shade, wind and temperature vary not only on site, but also between bioretention areas. As a result, the designer may need to consider the placement of each plant. An example would be to consider placing evergreen trees or other wind tolerant species on the northern end of a bioretention area, against cold winter winds.

BACK TO PLANT MATERIAL GUIDELINES

The above information was derived from the Prince George's County Bioretention Manual.

Drawing credit: Prince George's County Bioretention Manual.

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The information on this website was compiled by T.E. Scott & Associates, Inc. from various sources.

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Last modified: 10/23/09