CHARLOTTE – As Pam and I were riding through town today watching the rain come down, hard at times, and considering what our weekly landscape column should be about, the answer was right there before us – Rain Gardens!
A rain garden, also described in technical terms as a bioretention facility, is a designed landscape site that increases stormwater runoff absorption by the soil. This in turn can be used to treat polluted stormwater by reducing the flow rate, total quantity and pollutant concentrations in runoff from mostly urban areas with greater impervious surfaces such as paved roads, parking lots and driveways. The plants and soil that make up the rain garden retain stormwater and slow down runoff infiltration. This also serves to filter pollutants carried by the urban runoff. Rain gardens can provide a method to basically capture and reuse the rain, reducing or eliminating the need for additional irrigation.
Rain garden plantings usually include wetland-type vegetation such as shrubs, wildflowers, ferns, and small trees. The plants take up nutrients and water that flow into the rain garden and release water vapor back into the atmosphere. Plant root systems become channels for the stormwater to filter into the ground. Root systems enhance soil permeability, provide moisture redistribution and sustain microbes that help break down organic compounds, some being pollutants, and also remove nitrogen.
Additional benefits, to name a few, include improved water quality through filtration in nearby bodies of water, restored groundwater supply, reduction of pollutants that runoff into the stormwater sewer system, flood control, the creation of an attractive landscaping area with diverse plant life and the encouragement of wildlife.
If you are considering creating your own rain garden its advisable to consult with an experienced landscaper or landscape architect. A successful and well-maintained rain garden will be one of the most significant landscape projects you undertake that protects the environment in so many ways.