Rain gardens are depressions created in the landscape that work by capturing water runoff and holding it a couple of days, allowing it to slowly drain into the soil. They are usually sized to capture the first flush of runoff from storms. This runoff contains most of the pollutants. In urban areas were runoff is frequent, rain gardens can help rid the earth of pollutants as well as provide beauty to an urban landscape.

Rain gardens are a relatively new concept.

They are designed to be small, yet effective. The retained water percolates down through the soil, trapping sediment and allowing nutrients to be used by plants placed in the rain garden. During rains, more runoff can come into the garden than it can hold, so it is important to give the excess water a place to go. For this reason, it’s best not to place a rain garden near a well or septic system.

Some yards, especially properties located in environmentally sensitive areas, such as those adjacent to streams or lakes, provide ideal situations for rain gardens. For example, when it rains, runoff from a road may wash fertilizer and soil across a lawn and down a sloped driveway before it then pools in a low spot by a stream. During larger storm events, the runoff may was directly into the stream- not the best scenario for the landscape or for water quality.

Rain gardens aren’t difficult to build. The typical rain garden requires a depression in the landscape to collect rain and snowmelt. This can be as large or as small as you want, but keep it at least 10 feet from your house to prevent seepage that can ruin your basement and foundation. Also, resist the temptation to locate a rain garden in a place where water already forms large puddles, as this indicates an area where water migration to deeper layers is already slow.

Put the garden in the sun, either full or partial, but not under a tree, as it will damage the tree’s roots. Locate it in an area where downspouts, runoff from walks or drives, or other natural water collection devices provide water. If you live in an area of heavy rain or deep snow, provide a drainage ditch or culvert to another rain garden or to the street.

Contrary to popular belief, rain gardens do not attract mosquitoes. Mosquito eggs survive only in water that stands for a number of days; most rain gardens dry in a matter of hours. Water loving native plants can survive in dry conditions as well, so resist watering them during dry spells, or they will get too tall, and droop in an unattractive fashion.

In addition to roadways and other hard surfaces, most urban and residential areas are primarily grass. Grass, or turf, does not percolate water well and requires a regular application of fertilizer and water to continue looking attractive. A rain garden, which is in essence a mini-wetland, mediates these problems, provides habitat and soothes urban anxiety.