Proper soil is essential for a rain garden, because a rain garden which does not absorb rain water will do little to prevent runoff! To make sure that your garden will operate effeciently, there are a couple simple tests you can do to determine the type of soil that you presently have.
First, place a small amount of soil in the palm of your hand. Add some water to the soil until it is moldable. Squeeze the soil, and when you release it, see if the soil maintains its shape. If it does not maintain its shape, the soil is sandy and will do very well as a rain garden.
If it does maintain its shape, perform the second test. For this test, squeeze the ball of soil between your index finger and thumb to form a ribbon extending above your hand. Keep extending the ribbon until it breaks. If the ribbon was less than an inch, the soil is silty. If it is longer than an inch, the soil is predominantly clay. If you have clay soil, mark yes for this question and consider amending the soil by adding compost and sand. Learn more about amendments by clicking the help question for the fourth question.
