Hibiscus coccineus aka Scarlet Rosemallow

Hibiscus coccineus is a perennial in the mallow family. Common names include scarlet rose mallow and swamp hibiscus. It comes from wetlands in the southeastern United States. Its native range includes Alabama, Georgia, and Florida. Marshes and swamps provide its natural home. In gardens, it forms an upright clump with a woody base.

Garden height varies between the sources. Missouri Botanical Garden gives 3–6 feet [0.9–1.8 metres]. UF/IFAS gives 4–8 feet [1.2–2.4 metres]. Spread reaches about 3–4 feet [0.9–1.2 metres]. Growth is fast, and the plant has an open shape. Thick, reddish stems carry green leaves in an alternate pattern. The leaves have slender lobes that spread like fingers. Each lobe has teeth along its edge. The plant sheds its leaves, with no marked fall color.

Red flowers appear from June to September. Each bloom has five petals and a clear central staminal column. Sources give flower widths of three to six inches. Blooms grow from the upper leaf axils on long stalks. Butterflies and hummingbirds visit the flowers. The fruit is dry, narrow, and half to one inch long. It draws little attention beside the large blooms. The plant offers little winter interest after its leaves fall.

Give this plant full sun or light shade. Too much shade leads to weak growth and fewer flowers. Keep the soil moist through the growing season. It accepts sand, loam, clay, and acidic soil. It also withstands long floods, summer heat, and humid air. UF/IFAS reports some drought tolerance, but moist sites suit it well. Salt tolerance is poor. Missouri Botanical Garden lists USDA zones 6–9; UF/IFAS lists 8–10. At the cold end, use a sheltered site and winter mulch.

Use it behind shorter plants in a mixed border. Groups also suit rain gardens and pond or stream edges. Taller stems may need stakes to stay upright. Deer resistance adds value where browsing causes problems. UF/IFAS does not identify it as invasive. Gardeners can raise plants from seed or divide established clumps. Aphids, scale, whiteflies, and Japanese beetles may attack it. Grasshoppers can chew leaves and buds, spoiling the flower display. Stalk borers may also occur. Disease risks include blight, canker, rust, and leaf spots.