Culture
Easily grown in organically rich, medium moisture, well-drained soils in full sun. Tolerant of a wide range of soil types. Will self-seed aggressively.
Noteworthy Characteristics
Hibiscus trionum is a weedy annual thought to be native to tropical and temperate Eurasia, although its exact origins are uncertain. It has escaped cultivation and naturalized by self-seeding throughout much of the world where it is often found along roadsides, railroad tracks, in waste areas and open fields. Multiple branching stems reaching 1.5-2' tall emerge from a single taproot and are clad with long-stalked, palmately divided, coarsely-toothed, dark green leaves (to 3” long) in three (infrequently five) parts. Lower leaves may be entire. Solitary white to pale yellow flowers (to 2” across) with dark purple centers bloom from the leaf axils from summer to frost. Flowers give way to bladder-like seed pods.
Genus name is the old Greek and Latin name for mallow.
Specific epithet means "three-parted" in reference to the leaves of this species.
The common name flower-of-an-hour refers to the relatively short amount of time individual blooms are open.
Problems
No serious insect or disease problems. This plant is known to self-seed and spread aggressively in gardens, croplands, roadsides, orchards, and other areas with bare, disturbed soils.
Uses
Can be used in beds, borders, cottage gardens, and containers. Carefully consider the ability of this plant to be a weedy, aggressive self-seeder before adding to your landscape.