Intro/Brief Description

Hibiscus

Family: Malvaceae

Genus: Hibiscus

Hibiscus belongs to the mallow family, Malvaceae. It is the largest genus with over 200 diverse species of annuals and perennials, shrubs and trees, and thousands of registered cultivars.

The name "hibiscus" comes from hibiskos, the Greek name for the common marsh mallow. Interestingly enough, the marsh mallow is not actually a hibiscus, but a close family member, Althaea officinalis.

In the past, ancient Egyptians believed tea made with red hibiscus flowers would act as an aphrodisiac in women, and fobade their drinking hibiscus tea. In China, the hibiscus appears on Chinese porcelain plates dating back to the Ming dynasty (1368–1644) and on ancient Chinese silk tapestries. Plants of the genus Hibiscus have been known in gardening circles of the western world since at least the late 1600s.

Today hibiscus are appreciated for their showy flowers and long bloom time. It is the state flower of Hawaii, and the national flower of Malaysia and South Korea. In some Caribbean coutnries the flowers are often carried in wedding bouquets as they are belived to ward off bad omens.

Besides the beautiful blooms, some species of hibiscus are used for things such as paper making, as a vegetable, to make teas and jams, and the fibers from one variety is used in Polynesia to make grass skirts. Extracts of some species are believed to prevent constipation, bladder infections and nausea, and help high blood pressure, but results of studies on these effects are in debate. Cotton (Gossypium) is a close cousin in the mallow family.

One thing is certain, hibiscus is a diverse, beautiful and useful plant.

Examples

The most well known of the hibiscus are the hardy group (H. coccineus and H. moscheutos) and tropical varieties (H. rosa sinesis).

In the hardy group, grown in zones 4 –10, there are varieites such as Kopper King with mahogany foliage and plate size blooms, Lord Baltimore with brilliant red petals, and Lady Baltimore with 6-8” pink flowers, growing about 4-5’ tall. Disco Belle is another popular variety with large flowers, but is a semi-dwarf, growing only 2 1/2’ tall.

Tropical or Chinese Hibiscus, H. rosa sinesis (Rose of China), is evergreen in the lower south. While tropical hibiscus can reach 30’tall in the tropics, it’s seldom over 15’ tall in the US. There are thousands of cultivars, with thousands of colors and combinations of colors (no true blue or black however). Blossoms are from 2" in diameter up to 10-12" and can be singles or doubles. Some bushes will only grow a foot in several years while others may grow to 15' if left undisturbed in the ground. There is great variety in this family.

Not as well known outside of the Gulf State is the Confederate Rose, or Hibiscus mutabilis. It grows 8-10 feet tall in zones 7-10, with fuzzy green leaves and single or double blooms in the fall.

Gardeners may also be familiar with anaother member of the hibiscus family, H. esculentus, better known as okra.

Also a member of this family, Rose of Sharon, or Shrub Althaea (H. syriacus) is a deciduous shrub or small tree up to 12’ tall. The flowers of this woody shrub are up to 3 inches across and come in several different colors. It is late to break dormancy in the spring, and resembles a bush covered with hollyhock flowers in the summer.

Special Features

One of the best features of hibiscus is the non-stop blooms from midsummer until frost. Most varieties produce an abundance of nectar, and thus are attractive to both butterflies and hummingbirds. It is a great background plant in beds and borders, or used as an accent plant. It can also be used in meadow plantings, at the edge of streams or ponds, and at the seashore. Once established, it is drought tolerant and heat tolerant. Hibiscus can also be grown in containers, most notably the tropical varieties.

Hardiness

The hardy varieties will survive in zones 4 – 10, but do best in zones 5-8. Tropical hibiscus can be grown outdoors in zones 8-10, but needs protection where winter temperatures frequently drop below 30F. If temperatures go much lower, hibiscus should be grown in containers and sheltered indoors over winter, or treated as an annual and discarded it at the end of the season.

Growth Habit

This varies by species, but generally hardy and tropical hibiscus plants have an upright, multi-stemmed growth habit. The Rose of Sharon has an up-right vase shape. The average height is 3-5’, but varies from 2 ½’ with the Disco Belle cultivars, to 10’ with the Confederate rose, and up to 12’ for the Rose of Sharon.

Bloom Time

The abundance and various colors of blooms are one of the best characteristics of this genus. Flowering generally starts mid-summer and continues to frost. On most plants, the blossoms only last one day, but there are always more in bud ready to replace the spent blooms. Removing faded flowers will help increase and prolong flower production.

Propagation

Although hibiscus can be grown from seeds, getting a pod to form on a plant can be difficult, so the more common method of propagation is by cuttings or division in the spring.

However, growing plants for seed is how new varieties are developed, as plants grown from seed will produce a plant and flower with qualities from both parents – the one that supplied the pollen, and the one that made the seed pod. Some of the flowers may be magnificent, and others inferior to the parent plants. The seedling produces genetically unique flowers, and until rooted or grafted is the only plant that can produce that exact blossom.

Germination OR Cuttings

Seeds should be soaked before they will germinate due to the hard seed coat. Scarification – nicking the seed coat with a sharp knife – will also help allow the water to penetrate. Once the seeds are ready, place them in a bowl with very hot water (Not boiling! No more than 190F). Use a large amount of water so it won’t cool off before the seed coat has time to soften enough to allow germination. Leave the seeds in the water over night.

Plant the seeds 1/16” (1.5cm) deep in sterile seed starting medium in February/March. Germination takes 7-14 days at 70-75°F (20-25°C). Once the seedlings are large enough to handle, transplant them into 3” pots. Gradually acclimatize them to outdoor conditions and plant them in late spring after all danger of frost has passed.

Chinese hibiscus species are best propagated from softwood cuttings taken in May, June or July. Cuttings should be about 3/8 inch in diameter and 6 to 12 inches long. Remove all but the top two or three leaves. They can also be propagated from semi-hardwood cuttings taken from mid July to early fall. At this time the wood is reasonably firm and the leaves are all of mature size.

Hardy hibiscus species can be rooted anytime there is new growth available, but usually works best in the spring. Use cuttings about pencil sized diameter about six inches long. Take off the lower leaves, leaving only 2 or 3 leaves at the top. They can also be propagated by division in the spring, but do not usually tolerate division in the fall.

Transplanting

Hibiscus is easily grown but difficult to transplant. It doesn’t like having its roots disturbed, and can go from being healthy to scraggly with a careless move or even vigorous weeding around the roots.

Soil

Widely adaptable to a wide range of soils, including wet soils. The ideal is loamy, but not too heavy soil. Adding compost or peat moss can help.

Irrigation

Needs to be watered regularly, loving moist to wet soil.

Sunlight

Generally speaking, does best in full sunlight, though some varieties can tolerate some shade. Enjoys the heat of summer.

Care

Once hibiscus is established, they need very little care. However, a mulch of compost in the spring to feed all those blossoms can be helpful.

Pests

They are resistant to most pests, but can occasionally fall prey to Japanese beetle, aphids, scale and whiteflies.

Disease

May occasionally fall prey to leaf spot fungus, blights, canker or rust.

References

Fell, Carolyn & Derek (1995). Guide to sun gardening. Spring Hill Nurseries.

Bender, Steve, editor (1998). The southern living garden book. Alabama: Oxmoor House.

Macunovich, Janet and Nikkila, Steven (1996). Caring for perennials, What to do and when to do it.: Storey Publishing, LLC.

Halpin, Anne (1996) Horticulture gardener’s desk reference. New York: Macmillan.

Calkins, Carroll, editor (1983). Illustrated guide to gardening.Readers Digest: New York.

Bush-Brown, Louise & James (1996). America's garden book. New York: Brooklyn Botanic Garden.

Lawton, Barbara Perry (2004/2005). Heavenly hibiscus, plants and garden.. Brooklyn Botanical Gardens Volume 19, No. 3 Fall 2004/Winter 2005.

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