Several landscape plants tolerate wet sites
By Tim Daly
Gwinnett County Extension Agent
Many homeowners frequently encounter areas in their landscapes that have poor drainage and are continuously wet. The excessive rain over the past year has increased the severity of this problem. Many of the most popular landscape plants decline and perish if the soil stays too wet. Most plants are unable to tolerate soil that has poor drainage because it reduces air infiltration. Since the roots require oxygen to function, the plants suffocate. Some plants can survive under these conditions, but they are stunted and susceptible to pests. Additionally, poorly drained soils can increase the likelihood of fungal root rot disease. Some plants are more adapted to wet conditions than others. Consider using them in these areas where other plant material is difficult to grow.
Several trees thrive in wet soils. Red maples can tolerate damp sites. They are attractive, easy to maintain, and many varieties have a brilliant red fall color. River birches thrive in wetland areas and by river banks. They tolerate flooded areas. However, the tree has a tendency to drop leaves during dry spells. Make sure they are planted away from walkways, driveways, patios, any other places where the leaf litter would be a nuisance. The bald cypress tree, a deciduous conifer that has a pyramidal growth habit, is native to swamps and wetlands throughout the Southeast. Weeping willows do well in wet soils, and they are frequently planted by retention ponds and other water bodies. Also, several oak trees, such as pin oaks, water oaks and willow oaks can grow under these conditions.
Some shrubs are adapted to growing in poorly drained sites. Yaupon hollies, which range from the size of small trees to shrubs, are native to wetlands in South Georgia and thrive in heavy clay soils. Wax myrtles, which have scented leaves and also native to South Georgia, are commonly planted in the landscape and can handle a variety of site conditions. Virginia sweet spire and summersweet, or clethra, have similar characteristics and can tolerate wet soils as well as drought conditions. They grow to a height of three to five feet, with oval shaped leaves, and white flower clusters. The summersweet blooms in May whereas Virginia sweetspire has blossoms in August. The American beautyberry, a native, has flower clusters on its stems by its leaves followed by small purple or white fruit, which birds love to consume.
Several herbaceous flowering plants thrive in damp conditions. The swamp hibiscus is native to wetland areas and marshes. It has showy, bright scarlet to red flowers that bloom continually from June to September. Canna lilies produce showy flowers that vary from red to orange to yellow. They will bloom continually until frost if the old flower heads are removed. Some cultivars have striped or bronze foliage. Cast iron plants, or aspidistra, have long, dark evergreen leaves and reaches a height of one to two feet. It can thrive in deep shade and will tolerate wet soils and prolonged dry conditions. Several species of irises, such as the yellow flag iris, the blue flag iris, Louisiana iris and Siberian iris, can handle damp soils. Yellow flag irises and Louisiana irises can grow in several inches of water and are frequently used in water gardens. Even mints, which do not produce attractive flowers but have scented leaves that are edible, do well in moist sites. However, they have invasive tendencies and their growth pattern needs to be kept under control.
Unfortunately, turfgrasses, vegetables and many other plants will perish if planted in soils that have poor drainage. However, there are many alternatives that tolerate and even prosper in waterlogged soil. If you have any part of your home landscaper that has a tendency to stay wet for prolonged periods of time, consider using some of these plants that do well under these conditions.
Timothy Daly, is an Agricultural and Natural Resource Extension Agent with Gwinnett County. He can be contacted at 678-377-4010 or firstname.lastname@example.org