Heavenly Hibiscus: Long-Lived, Easy-Care Beauties
Species and cultivars of the genus Hibiscus are enjoying an era of increasing popularity as garden designers and home gardeners alike discover and rediscover their attributes. Vigorous. Tough. Easy to grow. Long-lived. Boasting spectacular flowers that bloom in a rainbow of colors throughout the growing season. Who could ask for more from ornamental plants!
Hibiscus is a diverse genus made up of roughly 220 species of annuals, herbaceous perennials, shrubs, subshrubs, and trees, which grow wild in many tropical, subtropical, and warm-temperate regions around the world. It is the largest genus in the Malvaceae, or mallow family. Many plants of this family are useful ornamentally, while others are sources of fiber, food, and medicine. The best known and most valuable economically of all the mallows is cotton (Gossypium).
Plants of the Malvaceae share certain floral characteristics. Each mallow flower has five separate though often overlapping petals of equal size. The stamen filaments (thin stalks that support the pollen-producing anthers) are fused, forming a sheath around the style (the elongated central tube growing out of the flower's ovary). Flowers are mainly funnel-shaped, but some are flat, like dinner plates—or, more picturesquely, miniature windmills.
The flowers of most Hibiscus species open in early morning and begin to droop and wilt by late afternoon. Most flowers last but one day, although a few varieties can brag of flowers that last two days or more. While most hibiscus flowers have no scent, some have modest fragrance. Flower sizes range from a prim two inches to a flamboyant foot or more in diameter. A wonderful bonus to growing hibiscuses is that many of them attract hummingbirds and butterflies.
Hibiscus in History and Art
The name "hibiscus" comes from hibiskos, the old Greek name for the common marsh mallow. A tall perennial, originally native to Europe and now widely naturalized in the eastern United States, the common marsh mallow is technically not a hibiscus at all but rather a close family member, Althaea officinalis.
In ancient Egypt, hibiscus flowers were associated with lust. The Egyptians believed that tea made with red hibiscus flowers and sepals could induce licentious cravings in women. As a result, for many centuries Egyptian women were forbidden to drink hibiscus tea.
The hibiscus plays an unusual part in the cultural traditions of some Caribbean countries. Hibiscus flowers are often carried in island wedding bouquets because they are believed to ward off bad omens.
Plants of the genus Hibiscus have been known in gardening circles of the western world since at least the late 1600s. There are indications that the very popular China rose (Hibiscus rosa-sinensis) was introduced to the Chelsea Physic Garden in London in 1731.
China has had a long love affair with the hibiscus. The flower appears on Chinese porcelain plates dating back to the Ming dynasty (1368–1644). Hibiscuses also appear on ancient Chinese silk tapestries.
A recent art exhibition, Treasury of the World: Jeweled Arts of India in the Age of the Mughals, at the Saint Louis Art Museum, showed that tropical hibiscuses were also prominent features in the art of the Mughal Empire (1526–1858), which included much of India, Bangladesh, and Pakistan. The hibiscus motif appears on an exquisite gold and enamel lidded cup from the mid-17th century. The handle of the cup lid was crafted into a hibiscus bud, ruby red with golden sepals.
How to Grow
For convenience, hibiscuses can be divided into three groups: tropical, hardy, and rose of Sharon. Tropical hibiscuses, although tolerant of some shade, will be healthiest and most productive in full sun. The best soil is well draining, of good texture, and highly organic, with a pH of between 6.2 and 6.5. Regular mulching will help add organic matter to the soil, conserve moisture, moderate soil temperatures, and keep weeds from growing.
While hardy hibiscuses (hardy to USDA Zone 5) will thrive in full sun with moist, fertile soil that is of good texture, they are so adaptable that they can tolerate some shade, ordinary soil, and dry conditions once they have recovered from transplanting. They can endure harsh weather and environmental extremes amazingly well.
Tough and hardy are words that characterize the rose of Sharon species (Hibiscus syriacus) and its many cultivars. Also hardy to Zone 5, these woody shrubs grow well in full sun to partial shade and adapt to most soils, except those that are either very dry or very wet. Rose of Sharon does best in moist, well-draining soil that has been supplemented with organic matter. It is pH adaptable. It is also tolerant of salt air and so makes a good choice for seaside properties. Rose of Sharon self-seeds prolifically and is known to be invasive in certain areas (for example, in Tennessee). Sterile triploid cultivars have been developed that don't have aggressive tendencies.
Here are brief profiles of some of my favorite tropical, hardy, and rose of Sharon hibiscuses.
Hibiscus schizopetalus (Japanese lantern)
Bearing finely dissected petals on three-inch-wide pendulous flowers, this slender evergreen shrub can grow up to ten feet tall. Flowers are pink or red with long slender staminal columns that extend well beyond the petals.
H. rosa-sinensis 'Brilliant Red' (China rose)
Bright red, single, five-inch-wide flowers grow on this reliable bloomer, one of the TradeWinds series. A bushy evergreen shrub, it can reach four to five feet tall if not pruned.
H. 'Blueberry Hill'
This hybrid hibiscus produces seven-inch-wide light blue flowers with a pinkish overcast. A fast grower, it makes a great cover-up plant for outdoor cultivation in subtropical climates.
H. coccineus (scarlet hibiscus)
Native to the southeastern U.S., this four- to six-foot-tall woody perennial has handsome, deeply lobed, glossy leaves and six-inch-wide bright red flowers.
H. moscheutos 'Blue River II' (swamp rose mallow)
Pearly-white flowers grow to the size of dinner plates on this tall (up to eight feet), strong-growing perennial. They make a great impact when they reach full bloom in summer.
H. moscheutos Disco Belle Series (swamp rose mallow)
This cultivar series includes white, pink, rosy-red, and red strains. Often grown as annuals, they are a compact version of the swamp rose mallow, growing to a height of only 20 to 30 inches.
Rose of Sharon
Profuse, single, five-inch-wide snow-white flowers with crinkled edges grow on this erect prize- winning triploid shrub. Petals are waxy and heavily ruffled on the edges. Flowers remain open for more than a day.
H. syriacus 'Helene'
This is an upright triploid shrub with abundant single flowers that are large and white with dark red edges and red veining.
H. syriacus 'Notwoodtwo' White Chiffon
Anemonelike flowers of pure white are the significant characteristics of this 1990s cultivar. The flower form is totally new to rose of Sharon: Each flower has a puff of staminal petals in the center.
Designing With Hibiscus
Use tropical hibiscuses, such as cultivars of Hibiscus rosa-sinensis, outdoors as perennial shrubs in Zones 11 and 12, or as annuals in colder climes. As colorful foundation or base plantings, as specimens, or in massed plantings, these hibiscuses are beautiful workhorses. As container plants, they provide instant decor to patio, lanai, or doorstep. Standard forms that are grafted to look like little trees provide instant color and structure to the garden.
The often gigantic flowers and comparatively large scale of many of the hardy hibiscuses, such as our native H. moscheutos (swamp rose mallow), make these plants top choices for hedges or massed plantings in large-scale landscapes. For the best hedge effect, plant them in a staggered row. Although hardy hibiscuses will excite "oohs" and "ahs" from admirers because of their large floral dimensions, many gardeners believe they make their best impression when used as background plants on the perimeter of a property or in a perennial bed or border.
Use the bold shrubby forms of rose of Sharon bushes in shrub beds and borders to create rich color schemes during the flowering season, from summer to fall. Rose of Sharon is superior for screening swimming pools or disguising unsightly fencing. These shrubs are also a good choice to plant against a large bare wall of a garage or house.
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