In the heat of the summer, hibiscus are popular ornamental plants that can add a touch of tropical flare to any landscape. The genus Hibiscus includes more than 300 species, including two that are native to Missouri.
These plants have a long history of cultivation, beginning in the 17th century when hibiscus from Asia were introduced to Europe. These species eventually made their way around the world to places such as Hawaii, Australia, and New Zealand where breeding and hybridization took off in the late 19th century. Today, selections of both tropical and hardy hibiscus are widely available for use in the home garden.
Hibiscus rosa-sinensis: When most people think of hibiscus they probably imagine Chinese or tropical hibiscus and its hybrids, which are by far the most commonly sold. Although this species is no longer known from the wild, it is believed to have originated in eastern Asia and is now widely cultivated around the world. Many of the most popular cultivars are hybrids that were originally bred for the gift plant industry. They have glossy, dark green leaves and 4-8″ wide flowers in a variety of colors.
In frost free areas such as southern Florida, these plants are commonly planted as an evergreen hedge or screen, but in St. Louis they are often used as an annual for large container plantings. They can also be overwintered indoors or kept as a houseplant. Chinese hibiscus is sensitive to the cold, and may start to exhibit yellowing and dropping foliage if the temperatures dip below 60°F.
Hibiscus syriacus: Another popular hibiscus originating from eastern Asia is rose of Sharon. These shrubs take well to pruning and have a long bloom time, producing 3-4″ wide flowers from early summer through to fall. They are hardy, tolerating urban growing conditions, high heat, humidity, and cold winters down to around -15°F. One downside to this plant is that they are quite vigorous and reseed aggressively. Rose of Sharon is considered invasive in some areas, including Kentucky and Virginia. There are new, purportedly sterile cultivars being released, but use caution when choosing one for your landscape particularly in places where this plant is known to escape into the wild.
Missouri’s Native Hibiscus
Missouri has two native species of hibiscus, rose mallow and swamp mallow. Both make excellent plants for sunny, open areas of the garden that have moist soil, including rain gardens, low spots, or on the edge of a pond. These native species have been hybridized with another hibiscus native to the southern United States called scarlet rose mallow to create a group of plants known as hybrid hardy hibiscus. These shrubby perennials are characterized by their dissected leaves and large, “dinner plate”-sized flowers in shades of red, pink, and white. ‘Midnight Marvel’ is a hybrid hardy hibiscus cultivar that was selected by Garden Horticulture staff as a Plant of Merit in 2019. It features a compact growth habit and a profusion of 9-10″ wide, bright red blooms from mid-summer into early fall.
For more information, including tips about growing specific varieties of hibiscus and other popular plants, visit gardeninghelp.org.
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