Shoring up your shoreline

By Heather Kirk-Ballard

LSU AgCenter Horticulturist

Water is Louisiana’s most abundant resource, with more than 40,000 linear miles of rivers, streams and bayous and 400 miles of coastline, according to the Louisiana Department of Transportation and Development.

In addition to our many water bodies, Louisiana is no stranger to the rain. In 2021, we saw record rainfall, with many cities receiving the third-highest amounts ever documented. According to the National Weather Service, the 2021 annual rainfall total was 85.08 inches in New Orleans, 79.85 inches in Baton Rouge and 72.26 inches in Lake Charles.

Almost half of our state government agencies are involved in projects that protect and manage Louisiana’s water resources and levee districts. One major effort is flood control. According to the transportation department, 75% of Louisiana’s population and 60% of the state’s agricultural products are protected by levees.

When we take into account the many small ponds spread throughout, that number can get even larger. Shoreline loss can be a real problem for some homeowners and landowners — whether it be from erosion caused by wind and water or from wildlife such as waterfowl.

Plants can help shore up your shorelines. By utilizing a variety of plants, you can help prevent erosion and stabilize the bank. Native wetland plants play a large role in soil stabilization. Plants also help filter out debris and pollutants from the water and remove nutrients that contribute to the growth of algae.

Typically, a diverse selection of native plants — including herbaceous perennials, woody shrubs and trees — will do the best job. Shrubs and small trees create an understory to larger canopy trees; together, they create a buffer zone that can greatly reduce soil loss and runoff. Twenty-five feet of buffer is ideal, but the wider, the better to help reduce erosion.

Unfortunately, turfgrass does not make a good shore-stabilizing plant because it is not a wetland plant and does not grow well in water-saturated soils. Although turfgrass can survive at the water’s edge, its shallow roots do not penetrate deeply enough to stabilize the soil. Over time, the shallow roots of turf will be undercut by erosion, and the bank will recede. It does, however, do well beyond the shore at the tops of banks.

Some plants that can grow on the water side of the shore are pickerelweed (Portedenia cordata), soft rush (Juncus effuses) and powdery alligator-flag (Thalia dealbata).

For plants closest to the shoreline, choose plants that are adapted to water and have an upright growth habit that helps keep them constrained to the shoreline. Some of these plants include Louisiana iris (Iris spp.), soft rush (Juncus effuses), bulrush (Scripus spp.), lizard’s tail (Saururus cernuus), spider lily (Hymenocallis palmeri), swamp rose mallow (Hibiscus moscheutos), bog lily (Crinum amricanum), cardinal flower (Lobelia cardinalis), swamp sunflower (Helianthus angustifolius), southern blue flag (Iris virginica) and white-top sedge (Dichromena colorata).

Other perennials include swamp milkweed (Asclepias incarnate), Joe Pye weed (Eupatorium dubium), false indigo (Baptisia spp.) and tickseed (Coreopsis lanceolate). Native grasses that can be used are muhly grass (Muhlenbergia capillaris), panic grass (Panicum virgatum) and river oats (Chasmanthium latifolium).

Large deciduous trees over 30 feet tall used as the canopy for the understory are black gum (Nyssa sylvatica), bald cypress (Taxodium distichum), pond cypress (Taxodium ascendens), red maple (Acer rubrum), river birch (Betula nigra), nuttall oak (Quercus nuttallii) and willow oak (Quercus phellos), to name a few. Evergreen selections include southern magnolia (Magnolia grandiflora), live oak (Quercus virginiana) and spruce pine (Pinus glabra).

Small deciduous understory trees include fringe tree (Chionanthus virginicus), parsley hawthorn (Crataegus marshallii), possumhaw (Ilex decidua), red buckeye (Aesculus pavia) and ironwood (Carpinus caroliniana). Some evergreen small understory trees include dahoon holly (Ilex cassine), American holly (Ilex opaca), sweet bay magnolia (Magnolia virginiana) and red bay (Persea borbonia).

Large evergreen shrubs that can be grown as small trees include yaupon (Ilex vomitoria), wax myrtle (Myrica cerifera) and anise shrub. Some deciduous shrubs adapted to wet areas are chokeberry (Aronia arbutifolia), American beautyberry (Callicarpa americana), fothergilla (Fothergilla gardenia), winterberry (Ilex verticillata), possumhaw (Viburnum nudum) and Virginia willow (Itea virginica).

Evergreen shrub selections are inkberry (Ilex glabra), Florida anise shrub (Illicium floridanum), dwarf palmetto (Sabal minor) and wax myrtle (Myrica cerifera).

In addition to helping prevent shoreline loss, plants provide habitat for fish, frogs, birds and other wildlife. They also baffle wind and reduce wave energy. If you are experiencing loss of shoreline, check out local nurseries for the availability of these water adapted plants.

Louisiana iris make a great plant selection for a rain garden.  Photo by Heather Kirk Ballard LSU AgCenter.jpg thumbnail

Louisiana iris makes a great plant selection for wet areas. Photo by Heather Kirk-Ballard/LSU AgCenter

Bald Cypress trees planted along water edges help stabilize the soil.JPG thumbnail

Bald cypress trees planted along water edges help stabilize the soil. Photo by Ashley Edwards/LSU AgCenter

Muhly grass commonly has pink flowers but they also have white varieties. Photo by Heather Kirk-Ballard LSU AgCenter.jpg thumbnail

Muhly grass commonly has pink flowers, but white varieties also are available. Photo by Heather Kirk-Ballard/LSU AgCenter

1/28/2022 3:22:29 PM
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