Many of us are very familiar with the tropical hibiscus, called Hibiscus rosa-sinensis. These are typically not cold hardy for the majority of the state. They can, however, be landscape perennials in warmer areas south of interstate 10 and in slightly more northerly areas if you find a micro-climate of warm air.
The Cajun series of tropical hibiscus is very popular right now. They are known for their brilliant colors and petal arrangements.
Other hibiscus species that can be used in landscaping include the false roselle, rose mallows, Texas Star hibiscus and confederate roses.
Hibiscus acetosella, commonly referred to as false roselle and African rose mallow, is a great foliage plant for summer and fall landscapes. When planted in spring, plants can easily reach heights of 5 feet or more by fall. Prune every month or so for the first couple of months after planting to produce a bushy, slightly more compact plant.
Several varieties are on the market –Mahogany Splendor, Maple Sugar, Panama Red, Haight Ashbury and Red Shield. Mahogany Splendor has bronzy foliage in full sun. Most of the Hibiscus acetosella have reddish foliage. The Haight Ashbury variety has multiple foliage shades of cream, pink and burgundy. Panama Red has deeply cut foliage that is rich carmine red.
A new variety recently developed by the U.S. Department of Agriculture-Agricultural Research Service in Poplarville, Miss., is Sahara Sunset, but it is not yet available at retail garden centers.
Plants produce red flowers during short days in late fall and winter in Louisiana, but in order for this to happen, they must be protected from cold damage. Plants need full sun. They have great drought tolerance. Minimum irrigation is needed. Plants have upright growth forms. Space plants a minimum of 3 feet apart when planting. Plants are deer resistant.
Home gardeners should consider white and red flower forms of Texas star hibiscus (Hibiscus coccineaus). They are a hardy perennial, unlike the popular tropical hibiscus. Large five-petal flowers appear in early summer and continue through fall. Plants go dormant in winter and start re-growing from the roots in April. Birds, butterflies and bees are attracted to the flowers. Plants come back from the roots in the spring. Seed produced in pods in the late summer through fall can also be saved for later. They germinate readily.
Rose mallows are also very popular in Louisiana. Some folks may know these by the name disco bell or dinner plate hibiscus. They are root hardy perennials and come in an assortment of white, pink, rose and red flower colors. Huge 8-10 inch diameter flowers appear in May and go through the early fall.
Popular varieties include Peppermint Schnapps, Cherry Brandy and the Flare series, available in several colors. The rose mallows work well in well drained or poorly drained soils. More sun than shade is preferred. Hibiscus sawflies will eat foliage of these plants – this insect can lead to unsightly foliage damage by mid to late summer. Control with carbaryl.
Finally, Confederate rose (Hibiscus mutabilis) is popular in south Louisiana. Plants can reach 15 to 20 feet tall. The woody stems usually do not die back during winters unless severe conditions are present. Flowers of Confederate rose begin the day as white. By early afternoon, the flowers are light pink, and by evening, flowers are a rosy pink.
The LSU AgCenter grows these hibiscus family members and several others in the trial gardens at the Hammond Research Station. You can see more about work being done in landscape horticulture by viewing the LSU AgCenter’s Hammond Research Station website at www.lsuagcenter.com/hammond. Also, like us on Facebook by going to www.facebook.com and typing Hammond Research Station in the search box. You can find an abundant amount of landscape information for both home gardeners and industry professionals.