Hibiscus laevis aka Scarlet Rose Mallow

Hibiscus laevis is a herbaceous perennial called halberd-leaved rose mallow. Smooth rose mallow is another name for this plant. Sources also list it under the older name Hibiscus militaris. It is native to the eastern and central United States. Chicago Botanic Garden also includes Canada in its native range. In Missouri, it grows beside streams, rivers, ponds, and ditches. It also grows in swamps and other sites with wet soil. In Illinois, it grows in marshes and along stream edges.

The plant has an upright form with stout, smooth stems. It reaches 4–6 feet [1.2–1.83 metres] tall in gardens. Its mature spread reaches about 3 feet [0.91 metres]. The leaves have three lobes and reach 0.5 feet [0.15 metres] long. Their shape recalls the head of an old halberd spear. This leaf shape helps set it apart from other mallows. Its height suits the back of a planted border. Taller plants may need stakes to hold their stems upright.

The flowers have five broad petals that overlap each other. Their colour ranges from pink to nearly white. A maroon or purple eye marks the centre of each flower. A clear staminal column rises from the flower's centre. The blooms reach about 0.5 feet [0.15 metres] across. Flowers appear along the stems, from the base toward the top. Each bloom lasts just one day. The season runs from midsummer into fall. Missouri Botanical Garden lists August and September as bloom months. Chicago Botanic Garden gives a wider July-to-October season.

Grow this mallow in rich soil with plenty of organic matter. It needs moist to wet ground through the growing season. Full sun gives the best bloom and helps limit disease. The plant also tolerates some light shade. It handles summer heat and humid air while soil stays moist. Missouri Botanical Garden lists USDA zones 4–9. Chicago's Hibiscus laevis page gives zones 4–8.

This plant suits rain gardens and the edges of ponds. It also fits wet low spots, cottage gardens, and native plant beds. Its large flowers offer a strong focal point in borders. The blooms draw butterflies, and Chicago also lists bird interest. Missouri Botanical Garden reports low upkeep and no serious pest or disease problems. It also lists tolerance of deer and wet soil.