Sand dunes offer inexpensive and efficient protection against rising tides and rolling waves. Here's how to enhance and maintain them.
Each year ravaging storms erode beaches and flood homes, but some of that damage can be avoided with one simple and natural defense: the dune. In the past, many communities considered sand dunes and vegetation nuisances, but now they're recognized as important shore savers.
Dunes develop naturally when high winds blow dry sand inland. When the wind meets a barrier, it slows enough to drop the sand, which begins to accumulate. According to David Nash, a coastal management specialist for Brunswick County, North Carolina, it doesn't matter if they're natural or man-made; sand dunes offer excellent protection against erosion caused by storms, by slowing inland-bound water. "When you lose your dune structure, you leave everything open for destruction," David says. By encouraging larger and properly placed vegetated areas, you can enhance a significant line of defense for your shoreline. "Vegetation holds sand in place, and without it you lose the protection the dune affords," he says. Follow these simple steps for effective dune management.
• Choose the right sea grass. Dune plants prevent sand from moving, but only certain species can thrive in the face of salt spray, high winds, low nutrients, and little moisture. David recommends sea oats, American beach grass, bitter panicum, saltmeadow cordgrass, and seashore elder. Still, climate determines a plant's geographic range, so be sure to research the proper grasses for your shore.
• Buy native. In The Dune Book, authors Spencer Rogers and David Nash encourage coastal homeowners to plant indigenous species for increased stability. (This practice also helps build new ecosystems on the dunes.) They recommend buying plants grown from seeds or cuttings that originated within a 100-mile radius of where they will be planted.
• Dig deep. "The biggest mistake people make is planting too shallow," David says. Grasses need to be 8 to 10 inches deep in order to reach moist sand.
• Determine your season. Check with your supplier about the proper time of year to plant your grasses. "American beachgrass likes to be planted in winter," David says. "Sea oats are a warm-season grass, and they're best planted after the danger of frost has passed."
• Encourage growth. While most dune plants require little to no maintenance, it's essential to fertilize. "Most require two fertilizations per year," David says. "A small amount of fertilizer at the right time can increase both growth and spreading rate."
• Install sand fencing. If you don't want to build a dune from the ground up, opt for fencing. Similar to plant stems, they trap sand at their base. While available in a variety of materials, wire-bound wooden slats remain the most popular. The downside is that sand fences deteriorate, and require more maintenance than vegetation. Experts say they're more useful for steering foot traffic away from dunes than trapping sand.
• Build a walkway. Dunes and sea grasses can't stand up to repeated foot or vehicular traffic, so provide beach access via crossovers. In most instances, pathways should be elevated at least 3 feet to allow for dune growth.
Dune rules and building codes differ among states, so check with your local authorities regarding permits.