Naturally Kiawah Magazine Volume 37 | Page 28

Rain Garden Installation The shape of the rain garden is an important feature that will allow the space to function as intended . Installing a rain garden requires excavation of the site by digging down approximately 10 to 12 inches . The removed soil can be used to create a berm along the edge of the rain garden . The berm is a mound along the outer edges that is up to six inches high and up to 12 inches wide . Dips in the berm can be reinforced with river rock and serve as inlets , channeling water into the rain garden . The depressed shape of the rain garden and berm around the outer edges will help to hold water in the rain garden during a rain event , allowing time for infiltration .
Once the rain garden is shaped , amend the rain garden soil with compost and sand , creating a mix that is approximately 20 – 30 percent parent soil , 20 – 30 percent compost , and 50 – 60 percent sand . The mix will resemble a salt and pepper appearance ; the sand will assist with infiltration , and the compost will provide for healthy soils where plants and beneficial microbes will thrive . The rain garden ’ s established plants and healthy soil will do the heavy lifting of trapping and removing various forms of pollution found in stormwater runoff .
When selecting plants for the rain garden , choose from small trees , shrubs , perennials , and grasses . Consider plants native to South Carolina as these species are well adapted to local climates , which can be extremely wet or dry , much like a rain garden . After planting , apply three to four inches of hardwood mulch ; avoid pine straw or pine bark mulch as these materials will float . Mulch helps to retain moisture in the rain garden during times of drought , moderates soil temperature , and serves as a weed barrier .
Maintenance Maintain the rain garden by irrigating during periods of drought and during plant establishment . It is not necessary to fertilize the rain garden . Be sure to maintain plants by regularly pruning and removing weeds . Remove debris such as litter , leaves , and sticks from the rain garden to prevent clogging . If the rain garden fills in and is no longer a depression , remove the upper layer of material and reshape . Add fresh mulch as necessary .
Local Rain Gardeners Karen Piret and her husband , John , recently installed a small
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