A rainy summer, followed by extended periods of hot humid weather have left many gardens in Brunswick County a soggy, unproductive mess of weeds and cracked fruits and vegetables. If you found out that your lawn or garden turns into a small swamp during a rain event, now is a good time to think about planting a rain garden this fall. Rain gardens are attractive and functional additions to any home landscape that improve water quality by filtering out pollutants that cause significant impacts to rivers and ocean habitats.
What is a rain garden?
As urban areas expand, the ability of nature to filter out rain water is lost because impervious surfaces such as parking lots, roads, and driveways divert unfiltered water directly into waterways like the Cape Fear River. An increase in the amount of pollutants leads to a loss in plant and animal diversity, which directly impacts human beings. You can help mitigate the problem by adding a rain garden. A rain garden is a shallowly depressed area of your yard that intercepts and collects storm water so that it can infiltrate into the soil. Rain gardens improve water quality by cleaning and filtering pollutants from storm water that would otherwise end up in rivers and oceans.
A rain garden can be constructed on almost any home property where water can be allowed to soak in the soil for a few days following a rain event. An ideal location for any rain garden is near the house around downspouts since the majority of water collects here from roofs and downspouts; however, stormwater runoff, especially from homes can be redirected to just about any area of your yard that you wish. The easiest way to determine the location for your rain garden is to walk around during or just after a rain event to observe its flow pattern. A well-designed rain garden will collect and hold the 1st inch or so of rain, in which is contained the majority of pollutants and sediment that washes away from roofs, yards, driveways, and streets.
Rain gardens come in all shapes and sizes. In general though a typical yard it is about 10% of impervious surface, which includes roofs, driveways, and sidewalks. Once you have chosen the location and shape of your rain garden, dig about 6-9 inches down into the soil, which will represent the lowest point of your rain garden. When selecting plants, it is important to choose ones that can tolerate a range of water conditions, including very wet to dry at ground level. Since a well-designed rain garden only holds water for 1-2 days, adult mosquitoes will not have time to lay eggs.
Select the right plants
To begin choosing the appropriate plants for your new rain garden, it is best to first divide the area into three separate zones. The first zone is the area at or just below the ground level. This is where you will need to choose plants that need more well-drained soil. Dwarf goldenrod, tickseed, rudbeckia, false indigo, and moss pinks are perennial plants that make excellent choices for the drier parts of your rain garden. For the middle area of your rain garden, plants like gay feather, garden phlox, verbena, and the shrubs beautyberry and spicebush are good choices. Pink or white muhly grass also makes an attractive, fine-textured addition in either the first or second zone of your rain garden.
In the wettest part of the garden, also known as the basin, choose plants that can withstand longer periods of flooding. Perennial plants swamp milkweed and blue star provide spring and fall color, respectively. Blue star has small blue flowers in the spring and bright yellow foliage in the fall. Rain lilies like the Zephyranthes species, and many irises are bulbs that delight in long periods of flooding in a rain garden.
Rain gardens are a great way to improve water quality and protect natural resources so vital to the Cape Fear Region. Rain gardens, when well-designed can be an attractive and functional feature to your landscape.
For more information on rain gardens and plant selections, visit ces.ncsu.edu where you can submit questions via the ‘Ask an Expert’ link, or contact your local extension office: If you live in Pender County, call 910-259-1238; in New Hanover County, call 910-798-7660; in Brunswick County call 910-253-2610.
Sam Marshall is the horticulture agent with the North Carolina Cooperative Extension in Brunswick County. Contact him at firstname.lastname@example.org.