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The Future - Rain Gardens!
By Fred Peratt, Environmental Enhancements, Inc.
Ever wonder how to solve a severe erosion problem or control excessive surface water. Consider a Rain Garden: a viable solution to prevent surface run off and filter unneeded elements from entering our water sources.
A rain garden is a garden which takes advantage of rainfall and storm water runoff in its design and plant selection. Usually, it is a small garden which is designed to withstand the extremes of moisture and concentrations of nitrogen and phosphorous found in storm water runoff. Rain gardens should be sited close to the source of the runoff and serve to slow the storm water as it travels downhill, giving the storm water more time to soak into the soil and less opportunity to erode surrounding areas.
A rain garden may support habitat for birds and butterflies or it may be a formal landscape addition. What makes it a rain garden is how it gets its water and what happens to that water once it arrives in the garden.
The garden is a small bio-retention area where storm water is cleaned and reduced in volume once it enters the rain garden. Nitrogen and phosphorus levels and sediment in the storm water are reduced by the action of the plants and the growing media.
Rain gardens are designed to be drained within four hours after a 1” rain event. The plants selected for the bio-retention area need to be able to withstand both the extremes of flooding and drought. Plants on the upper edges often like it dry while the plants lower in the garden should be more adapted to flood conditions.
When preparing a rain garden the existing soils are amended with a very porous planting media, minimally to a depth of 8” and ideally to a depth of 2’- 3’. The lower the amount of soil amendment added when the garden is built, the more necessary it is to have plants adapted to prolonged periods of wetness.
Typical rain gardens are designed and planted with natives or native cultivars because those are most well adapted to a locality.
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