Rain Gardens are a creative way to collect and cleanse run-off water. Among the most important aspects of the garden’s design are: square footage, soil percolation, depth and choice of plants.
*Square footage of the garden should be 10% of the square footage of the area from which the run-off water is collected. (Are you collecting water from a slope in your yard? A roof? Both? Take acurate measurements.)
*The soil should have a percolation/absorption rate of half an inch to an inch of water per hour. This means that a garden with a six-inch depth (which is the recommended depth of a rain garden) should drain within 6 to 12 hours.
*Rain Gardens are best suited for perennial, native plants which can withstand times of drought and flood.
*Here’s a great list of rain garden appropriate plants: http://raingardenalliance.org/planting/plantlist