Hibiscus trionum seeds - Flower-of-an-hour

Hibiscus trionum, known as African Rose Mallow or Flower of an Hour, is a little-known ornamental plant, most often grown as an annual. Each flower lasts only one day, but the plant produces continuous flowering throughout the summer, from June to the first frosts. In flower beds, borders, or on a sunny terrace, its bicolour flowers possess a gently exotic charm.

Hibiscus trionum belongs to the Malvaceae family and originates from eastern Mediterranean regions, although this species has spread to subtropical and temperate climates across southern Europe and America. In Australia, it is considered invasive due to its ability to self-seed easily. This annual herbaceous plant, sometimes biennial, reaches between 50 to 80 cm in height. It forms a rounded clump composed of stems branching from the base.

The foliage of Hibiscus trionum is distinctive. The alternate, dark green leaves are deeply lobed, with 3 to 5 main lobes that further divide into smaller lobes. These lobes have toothed or slightly crinkled edges. The first leaves at the base of the plant are more rounded, while the upper leaves are longer and more deeply lobed. Each leaf can reach between 2 and 8 cm in length. This foliage gives the plant a light and airy texture. The leaves and stems are slightly hairy, quite soft to the touch.

The flowers of Hibiscus trionum measure approximately 6 to 7 cm in diameter. They are characterised by pale yellow to cream-white petals, contrasting with an almost black, dark purple throat. Each ephemeral flower lasts only one day and often opens under direct sunlight. The plant's fruits are lantern-shaped capsules containing kidney-shaped seeds, capable of self-seeding spontaneously. This prolific plant can produce successive blooms throughout the summer, provided it receives warmth and light.

Hibiscus trionum is used in sunny flower beds, flowering borders, or in containers on a terrace. Its dense habit and generous flowering make it an excellent background plant or the star of a summer bed. To create a harmonious composition, pair it with Creamy Yellow Shrubby Sage 'Melen', Aster cordifolius 'Little Carlow', and Perovskia 'Lacey Blue' for example. This combination provides a prolonged and delicately coloured flowering display.