SPECIAL TOPICS: HIBISCUS

The Chinese hibiscus, Hibiscus rosa-sinensis L., is probably the most popular and widely planted shrub grown in Florida. It is believed to be native to China and was introduced to Florida by way of the South Pacific and Hawaii.

Hibiscus varieties are selected on the basis of plant growth habit and size, the form and color of the flowers, and adaptability to specific environmental conditions. Plants range from low, spreading forms to upright varieties reaching 20’ (6 meters) in height. Some are compact and dense while others are open and thin.

Although the six basic colors are red, orange, yellow, white, lavender, and brown, there is a broad range of color combinations, color shades, and flower forms. Hibiscus flowers are characterized as single or double forms with variations in the number and arrangement of petals.

Hibiscus flowers are often used in flower arrangements. Picked flowers do not have to be placed in water but should be kept in a reasonably cool place. Hibiscus flowers may be saved for evening use if picked just after they have opened in the morning and refrigerated until needed.

Hibiscus are used in the landscape as informal hedges or screens, foundation plants, or background for other garden plants. They do not perform well as formal sheared hedges. The repeated use of a single variety in hedges and other mass plantings is usually more effective than a mixture of several varieties. Selected varieties may be trained to grow with a single trunk and are called "standards." Standards make attractive specimen plants for patios, terraces, and flower gardens.

Hibiscus breeders are still active in Florida as evidenced by the hundreds of named varieties found today. In general, the older varieties that grow well on their own roots are the most desirable for use in the landscape. Many of the newer varieties grow well only as grafted plants and are not widely available.

For more information and charts go to: http://edis.ifas.ufl.edu/MG020
Hibiscus in Florida. D. L. Ingram and L. Rabinowitz.Environmental Horticulture Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. First published: June 1990. Revised: March 1991, October 2003.


PLANTING HIBISCUS

The use of hibiscus as an evergreen shrub in Florida is limited to the southern half of the peninsula. The limiting factor for growing hibiscus in north Florida is low temperatures. Plants will be killed to the ground by 28 to 30°F (2 to 1°C) temperatures, but established plants may come out in the spring and bloom on new growth that summer. Hibiscus should be protected from cold northern winds by fences, buildings, screens, or trees. Hibiscus are not tolerant of salt spray or saline irrigation water.

The amount of sun required for optimal hibiscus growth and flowering differs with variety. Generally, half a day of direct sunlight is the minimum requirement.

A wide range of well-drained soils is suitable for hibiscus if proper fertilization is provided. A soil pH of 5.5 to 6.5 is preferred. Hibiscus grown on alkaline soils may suffer from micronutrient deficiencies and these are discussed in the fertilization section.

Container-grown hibiscus can be planted any time during the year, but transplanting in the yard is best done during the cooler months. The planting hole should be 1’ (30 cm) wider than the root ball and as deep as the root ball is tall. Hibiscus should be planted at the same depth as they were in the container or field. Staking may be necessary.

The novice hibiscus gardener often plants the hibiscus too close together. Plants should be spaced on the basis of their mature size. 3½’ to 4’ (1 meter) spacing is recommended for a hedge, but 4½’ to 5’ (1½ meters) is appropriate in garden areas and foundation plantings.

An organic mulch will conserve water, reduce weed problems, and help control nematodes. Good mulches include cypress or pine bark, oak leaves, or pine needles. Do not place mulch in contact with the hibiscus stem.

For more information and charts go to: http://edis.ifas.ufl.edu/MG020
Hibiscus in Florida. D. L. Ingram and L. Rabinowitz.Environmental Horticulture Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. First published: June 1990. Revised: March 1991, October 2003

CARING FOR HIBISCUS

Plants should be watered thoroughly after planting to prevent wilting until they are well established. The soil should not be kept continuously wet. They require well-drained soils and need regular irrigation during periods of drought. Hibiscus should be watered heavily once a week during dry periods with enough water to wet the soil to a depth of 12” to 18” (30 to 45 cm).

Regular fertilization is essential to maintain healthy and vigorous plants. Hibiscus bloom best when fertilized lightly and often. Three or four applications per year have proven satisfactory. The amount of fertilizer per application depends on frequency of fertilization and size of the plants.

Heavy pruning is best done in the early spring (February or March) and should not be done late in the fall or in the winter. Light maintenance pruning may be done any time of the year. Blooming is delayed and reduced if the plants are pruned too heavily. Plants can be pruned to maintain a desired size and shape without disrupting their blooming by cutting only the longest ? of the branches at one time.

Hibiscus can be propagated from seed or cuttings, or by air layering, budding, or grafting. Seedlings are grown primarily by hibiscus breeders. Cuttings will usually root in about six weeks and the plants produced will begin to flower in about nine months. Some varieties do not root readily from cuttings and air layering becomes a useful alternative.

Several types of chewing pests feed on hibiscus leaves, buds, or flowers at one time or another. Other pests damage hibiscus by sucking plant juices. These pests are generally more of a problem in areas with poor air circulation. Control of these pests can be difficult if large populations are allowed to develop. Generally, pests can be controlled with applications of contact or systemic pesticides. Routine inspections may reduce quantity of pesticides required. Hibiscus are sensitive to many pesticides. The safest time to spray is early morning and not in the middle of a hot sunny day. Always read the label before applying a pesticide.

Common diseases include leaf spot, canker, and mushroom root rot. Leaf spots are caused by various fungi and bacteria and controlled by picking off or raking up diseased leaves and destroying them. Canker is a fungus disease and controlled by pruning off and destroying all diseased wood. Mushroom root rot usually causes wilting and death a short time later. Dead or dying plants should be removed with as much of the root system as possible, and the soil should be replaced or sterilized before replanting.

For more information and charts go to: http://edis.ifas.ufl.edu/MG020
Hibiscus in Florida. D. L. Ingram and L. Rabinowitz.Environmental Horticulture Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. First published: June 1990. Revised: March 1991, October 2003