A rain garden is simply a pond-like excavation that is backfilled with a water-holding soil and compost mixture. Runoff from typical impermeable surfaces such as driveways, sidewalks, roofs, and patios is directed to flow into the rain garden via a buried pipe, swale, or rock-filled channel. A variety of plant species that can tolerate various degrees of saturated soil are then added to the entire rain garden area. The result is a beautiful addition to your landscape that also performs a very valuable function for your property, your neighborhood, and your region.

How They Function

The main function of a rain garden is to capture and filter stormwater runoff. The soil and plants inside a rain garden absorb the runoff and filter out any pollutants it carries while allowing it to percolate into the aquifer (water table), streams, lakes, or other waterways.

A rain garden is constructed in a way that allows it to capture and hold all the runoff that is directed into it, while letting that runoff slowly infiltrate into the soil. In case of a large rainfall event, it is necessary to have a "ponding area" above the surface of the rain garden soil mixture in order to store some of the runoff there. An outlet for any excess water is also needed.

When designed well, a rain garden can also function as a low-maintenance yet aesthetically appealing addition to your landscape. They usually need less maintenance than typical gardens and lawns, because they demand less pruning, no mowing, no fertilizers, and little to no additional watering. A rain garden can be designed to seamlessly blend into your existing landscape, or to stand out as a focal point. Rain gardens can be designed to also provide valuable habitat for songbirds, butterflies, and other beneficial insects.