Select a Spot for the Garden
A rain garden can work virtually anywhere. The size, location and effectiveness depend on things like the amount of rain water runoff that is directed into the garden, the rate at which water soaks into the soil and the plants that are selected. Areas along driveways or sidewalks may also be ideal spots for a rain garden.
Locate your rain garden where it will collect the maximum amount of rain water runoff -- but at least 10 feet away from the foundation of your house. Look first for a natural depression in your yard where water from a downspout may already naturally flow. Alternately you may have to plan to route water from the downspout to the garden through a grassy depression called a swale or through a buried plastic pipe. Placing your rain garden "down hill" from a driveway will maximize its ability to collect rain water that runs off the driveway. Your garden will grow best in an area with partial or full sun, but Fort Wayne's How To Manual also includes some ideas for shady gardens.
Determine Size and Depth
The size of you garden depends on how much rain water runoff will be going into it. You'll need to measure or approximate the area that will drain into the garden. You'll perform an infiltration test to find out how fast the water will soak into the ground. In general, for an area such as northeastern Indiana that has primarily clay soil, you can make the garden about 3" deep. Divide the area that will drain into the garden by 3 (the depth) to determine how large the garden should be. Fort Wayne has a Rain Garden Sizing Worksheet that will help with these calculations. You can also take a look at a Sizing Example.
When selecting plants, remember that your rain garden will be an attractive part of your existing landscaping that also helps to protect water quality.
You want the plants to help soak rainwater into the ground. So look for plants that have deep root masses. Native grasses and wildflowers typically have roots that go several feet deep. Native plants are low maintenance. Many can tolerate drought or short periods of standing water. Most of the plants shown on Fort Wayne's rain garden designs are perennials and will survive the winter in Northeastern Indiana. Native plants are also less prone to inset damage and disease.
When selecting plants for the rain garden, consider the height of each, the time when each one will bloom, the color and overall texture. By using plants that flower at various times, you can create a long blooming season. Fort Wayne's rain garden layouts include a variety of color and flowers that will bloom from spring well into fall. These can be found in the Appendices to the How To Manual
Click here to see lists of plants that are appropriate for use in the Fort Wayne area and for information about plants that may be aggressive spreaders or may be toxic to children or pets.