Scarlet swamp hibiscus (Hibiscus coccineus) is in the Malvacea family and is native to the Southeastern US. Hibiscus in Greek and Latin means mallow, and in Latin, coccineus means scarlet. Plant geeks, like me, are fascinated with knowing the meaning of scientific plant names.
This deciduous, woody perennial grows best in a sunny spot with fertile, moist to wet soils. It is a beautiful selection for wet areas and rain gardens but will also thrive in landscape plantings where the soil is kept damp.
The 10- to 12-inch, five-petaled, deep scarlet flowers bloom prolifically from August through September. Each flower may only last for a day, but plants will continually bloom throughout the late summer and early fall. The palmately compound, deep green leaves have deeply divided lobes. Scarlet swamp hibiscus will get 3 to 7 feet tall and 2 to 3 feet wide and is hardy in USDA Zones 6 to 10.
The plants will die back to the ground in the winter but will resprout again in the late spring. After a hard frost or freeze in the fall, do not cut back the bare stems. Wait until the fear of frost has passed in the spring to prune back the plant. This prevents water from dripping down into stems and freezing, which would cause cold damage to the crown of the plant.
The red blooms are a magnet for hummingbirds and butterflies. As with most hibiscus, deer do love to munch on the plants. Watch for Japanese beetles this time of year as they feed on both the foliage and flower petals. Aphids, scale, and whiteflies may also be problems.
For more information on growing scarlet swamp hibiscus, please see HGIC 1179, Hibiscus.