A rain garden is a depressed area in the landscape that collects rain water and allows it to soak into the ground. It can also be used to treat polluted stormwater runoff. Planted with the right grasses and flowering perennials, rain gardens can be a cost-effective and beautiful way to reduce runoff from your property. Rain gardens can also help filter out pollutants and provide food and shelter for butterflies, songbirds, and other wildlife.