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Why not add a rain garden to your landscaping? – Picayune Item

By Patricia Drackett

Director of the Crosby Arboretum and

Assistant Professor of Landscape Architecture Extension at Mississippi State University Extension Service

Recent columns have offered solutions to make your summer gardening a breeze, like using water-loving plants in the wet areas of your landscape. We often recommend a visit to the Crosby Arboretum Pollinator Garden to see the plants that thrive here, which can spark new ideas for low-maintenance species to incorporate into your own garden.

If you’re a regular reader of those tantalizing gardening magazines, you might have noticed an article or two about rain garden design. what are we talking about here? Rain gardens are designed to collect and retain rain, also known as storm water or “runoff”. They slow down water before it leaves your property and allow it to run off into the ground rather than being funneled immediately into a storm drain system.

As land becomes more “urbanized” or developed, the amount of paved surface increases. Water flowing over a paved surface moves much faster than over a lawn or wooded area. Because many communities still have stormwater and sewer systems that are connected underground, in heavily developed areas even small rain events can cause these systems to back up and overflow. Floods present many safety issues. Additionally, pollutants such as phosphorus, heavy metals, and nitrogen can be captured in the process and transported to streams and rivers in the area.

The Mississippi State Extension Service website (http://extension.msstate.edu/) is a great place to start learning how to create these gardens. Enter the keywords “rain garden” into the website search box to find information on the subject, including simple methods for calculating the size of your “watershed” so you can determine the appropriate size rain garden to accommodate runoff from your property, and recommendations for plants to use in those areas.

It is best to place your rain garden in a main drainage channel or in depressions where water tends to pool after a rain. It is also important to understand the type of soil offered by your site. Sandy soils are generally the best, as they will allow the area to drain quickly. Sample boxes for soil testing can be obtained at your local county extension office.

Rain gardens are sometimes misunderstood. A common misconception is that they will be a breeding ground for mosquitoes. However, a suitably sized rain garden only holds water for a short time after a rainfall, such as a day or two. By draining quickly, they won’t have the standing water needed for the pesky insects’ seven-day breeding period.

Another common myth about rain gardens is that they have to be deep, which they really aren’t. They don’t need to be located on steep slopes, but they can be great solutions for reducing erosion in those areas. In fact, the slope needed for a rain garden can be so gradual that you may have even walked right by a garden without knowing it! Most rain gardens are between four and eight inches deep. If it’s shallower than four inches, it may not provide the necessary capacity, and if it’s deeper than eight inches, it may not empty quickly enough. Water from your downspouts can be channeled into a rain garden.

The general components of rain gardens are a sunken or low area, a rocky area that slows the entry of water into the garden, a berm that functions as the “safety net” of the garden (this can be where your excavated soil is deposited if you need to remove it to create the proper capacity), and finally, hardy plants that can tolerate both extreme short-term flooding and long periods of drought.

Many native Mississippi plants make exceptional choices for rain gardens! Recommended native trees include red swamp maple, bald and pond cypress, black swamp gum, sweet bay magnolia, mayhaw, and wax myrtle. Native shrubs include inkberry and yaupon holly, saw palmetto, buttonhole, sweet summer, sweetspire, titi, and buckwheat. Recommended native perennials include Joe pye grass, Stokes aster, Texas star hibiscus, native iris, Coreopsis, and Liatris. Consider contrasting perennials with native grasses such as blue sedge, muhly grass, little bluestem or panic grass.

Sign up for an “Introduction to Birdwatching” walk with Jessica Martin, avid birdwatcher, on Saturday, July 16 from 9:30 a.m. to 10:30 a.m. Learn tips, resources, and gear available for beginners and others, in addition to common bird species found in the area. The cost is $2 for Arboretum members and $7 for non-members. Attend the Wire-Wrapped Jewelry Workshop on “Making a Pendant” with jeweler Connie Boyd of Unique Stones on Saturday, July 16, from 12:30 p.m. to 3:30 p.m. The $70 program cost is paid directly to the instructor on the day of the workshop in cash or check, and includes a chain, tools to use, sterling silver wire and your choice of a semi stone. -precious

Call 601-799-2311 to register for programs (pay on arrival). For more information, see our website calendar at http://crosbyarboretum.msstate.edu/ or visit our Facebook page. The Arboretum is open 9 a.m. to 4:30 p.m. Wednesday through Sunday and is located at 370 Ridge Road in Picayune at I-59 exit 4.