Rain gardens

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This article is about planted installations designed to capture surface runoff in an amended soil.
For more highly engineered systems, see Bioretention cells.

Schematic illustrating the components of a rain garden.
Disconnected downspout routing water into a rain garden.


Rain gardens capture roof, lawn and driveway runoff from low to medium density residential lots. These can be simple gardens constructed by the homeowner as a retrofit, or they can be professionally designed into a residential development.

Rain gardens are ideal for:

  • Capturing the flow from disconnected downspouts
  • Community design/build projects for raising awareness about stormwater capture and functional landscapes

The fundamental components of a rain garden are:

  • An amended soil mix
  • Suitable planting

Additional components may include:

  • A splash pad of rocks to prevent the downspout flow from eroding the soil
  • An overflow channel to another are of garden

Planning Considerations[edit]


Plant Selection[edit]

The design of a rain garden allows for several different planting zones.

Hydric Zone Criteria[edit]

Low Zone Often referred to as the extended detention or shoreline fringe area. This area is frequently inundated during storm events, and is well-drained between rainfall events.
Mid Zone Often referred to as the floodfringe area. 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.
High Zone Often referred to as upland area. 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.

Incentives and Credits[edit]

In Ontario

See Also[edit]

External Links[edit]