Answer: You probably want to focus on drought-tolerant plants, since the raised soil will drain more quickly and thoroughly than the surrounding area. The type of plants to use also depends on the soil type (is it pure gravel, topsoil, or a mixture?). If it's poor soil, you can keep it simple and plant a flowering groundcover like crownvetch, which spreads quickly and has gorgeous soft pink blooms. If the soul is rich enough to support it, or mix it up and plant shrubs and perennials through landscape fabric, and cover the fabric with mulch. Ornamental grasses that grow in clumps may be a fitting substitute for your lawn grass, and won't need mowing. A soil test is probably the best place to start to determine the limits of what will grow on the berm. Your agricultural extension office (ph# 919/732-9361) can provide you with information on soil testing. Once you have the results, submit another question through the Q&A page, and we can make specific recommendations for plant material. Best of luck!
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