Hardy Herbaceous Hibiscus
When many people think of hibiscus, they picture the tropical H. rosa-sinensis which is so often featured on Hawaiian shirts or tucked behind the ear of a South Sea islander, but there is a whole world of different hibiscus from tropical shrubs to small temperate zone trees, annuals, and herbaceous perennials. Gardeners generally include the woody-stemmed, root-hardy types in with this last group since the woody stems die to the ground each winter. These herbaceous hibiscus are some of the most reliable performers in the garden.
Depending on your taxonomist, the total number of species is about 225 and many selections and hybrids have been named. They are mainly used as ornamentals, but various species are used in skin care products, to make paper, as food (dried, fresh, and candied), and most widely as a tea. Having had several types of hibiscus tea, hot and cold, I would say the Jamaican type of tea with its added rum is indubitably the best. In fact, many of the other "teas" I've had the pleasure of experiencing around the world might be improved with a splash of Appleton Estate Reserve Jamaican rum.
The herbaceous hibiscus range in height from about 3'–10', usually with multiple stems erupting from ground level. In very mild winters, some of these plants can keep the tops alive through the cold season and into spring but generally look best if cut to the ground in winter anyway. The foliage is often palmately lobed and in the case of our native H. coccineus, palmately compound with narrow leaflets, but may be unlobed as well. Leaves of different species may also be glossy green, sometimes with reddish veins or incredibly fuzzy with a silver look. In all cases, the best hardy landscape performers have large flowers with typical mallow structure—five petals with a central staminal column that is proudly and unabashedly displayed.
The large flowers, often up to 8" in diameter, of some of the species and cultivars make them a favorite for use in the landscape as does their long flowering time. Many selections start flowering in June and don't finish until September. Quite a few of the showiest hybrids come from our native H. moscheutos and H. coccineus. These native hibiscus are found growing in the eastern United States in marshy, boggy areas but will perform admirably in less damp locations if given good garden soil. Flower color ranges from pure white to brilliant shades of pink and burgundy sometimes with bicolors and pinwheel effects as well in the more complex hybrids.
Herbaceous hibiscus respond well to added fertility and moisture so rich soils, supplemental irrigation, and added fertilizers will provide some oomph to the already considerable flower power. Sun is a requirement for all hibiscus to flower well and the shade-blessed gardener is mostly out of luck with this group. Dedicated gardeners can deadhead the seed capsules to extend the bloom until frost or the seed heads can be left for winter interest or dried arrangements. Japanese beetles can be a serious problem and will usually attack hibiscus in preference to any other garden plant and quickly skeletonize the leaves. We find our diverse landscape and natural predators will often take care of the problem. In general, hibiscus will recover once the Japanese beetles move on. Severely damaged plants can be cut to the ground and allowed to re-flush.
My current favorites include the deeply colored H. moscheutos 'Whit XX' (Cranberry Punch®) which stays a diminutive 30" or so tall with dinner plate, burgundy flowers admired by visitors as they walk down the entrance path towards the Ruby C. McSwain Education Center. I've also had a love affair with the white form of our typically red H. coccineus for many years, and we've planted it below the McSwain Center and the Klein-Pringle White Garden where it reaches 6'–8'. The thin-petaled flowers and finger-like leaflets add a finer texture than the typical hibiscus. In Asian Valley, the dominating summer form of H. makinoi which grows to 8' or more in height and width each season, makes for an exceptional display of felted, pale green maple-like foliage. In the late summer and early fall when much of the garden is thinking of shutting down, this Japanese hibiscus opens its pale pink, 5" flowers for a softly glorious end to the hibiscus season.
Whether planted in a bog garden, perennial border, or out by the mailbox, herbaceous hibiscus will reward gardeners with a profusion of showy flowers and boldly textured foliage with little care. The sturdy stems provide rambling room for small vines and support for floppy perennials. Use them to create exuberant displays as these are not plants for the dainty gardener.