Kosteletzkya virginica "Alba"

Seashore mallow is an erect, branching herbaceous perennial of the cotton family (Malvaceae), the same clan as hibiscus, hollyhock, and cotton, and the kinship shows in the flowers. Native to the brackish and salt marshes of the eastern United States, from New York and Delaware south to Florida and Texas, the species carries hibiscus-like blooms from midsummer well into fall, each a clear five-petaled cup around a central column of fused stamens. This selection, 'Alba', trades the usual soft pink for pure, clean white.

Every individual flower lasts only a day, but seashore mallow opens so many at once that a well-grown plant can carry dozens of fresh blooms at a time, a long, generous procession through the hottest weeks of the year. Bees, butterflies, and other pollinators work the flowers steadily, and the two-and-a-half-inch white cups glow against the coarse, softly hairy foliage, especially in the low light of morning and evening.

What sets seashore mallow apart from most garden perennials is a remarkable tolerance for salt and wet ground. Thriving in saline and brackish soils that would kill ordinary plants, and shrugging off periodic flooding, the species has drawn scientific interest as a salt-tolerant oilseed crop for coastal farmland. In the garden, that same toughness makes 'Alba' a natural for the difficult wet and salty places where little else will flower so freely.

Use this white seashore mallow at a pond or water-feature edge, in a rain garden, along a brackish shore, or toward the back of a sunny, moist border, where the tall stems and white flowers can rise above lower companions. Give full sun and steady moisture, pair with other moisture-loving natives such as swamp milkweed, blue flag iris, and cardinal flower, and cut the frost-killed stems to the ground in late winter. The clumping habit stays tidy and returns dependably each spring.