Tropical Hibiscus
By: Deb Willard

ABSTRACT

Tropical hibiscus can be easily propagated by seeds, stem cuttings, leaf cuttings, air layering or grafting. Under the proper care and conditions, tropical hibiscus exhibit beautiful flowers and foliage.

INTRODUCTION

Tropical hibiscus have glossy, dark green leaves, 3-4" red, pink, orange, yellow, single or double flowers. Tropical hibiscus are native to warm, sunny, humid places. They will not survive outdoors north of zone 9. They may be grown in n orthern climates if they are brought indoors before temperatures drop below 40o F at night. Inside, the plant must be placed in a bright, humid location. Artificial lighting and humidifiers will help to meet these requirements (Year ‘round Hibi scus).

Hibiscus thrive in light potting mixes such as Sunshine Mix or PRO-MIX. Hibiscus are heavy feeders and should be fertilized frequently. A dry fertilizer such as 10-10-10 works well.

Hibiscus are susceptible to phloem sucking insects such as aphids and white flies. These insects collect on the underside of leaves, new growth and flower buds. Systemic Insecticides are very effective in eliminating these pests. (Hibiscus Pruning, Fertilizer/Insect Control).

METHODS OF PROPAGATION

Tropical hibiscus may be propagated by seeds, stem cuttings, leaf cuttings, air layering or grafting.

Seed germination will be encouraged by bottom heating. It will take 6 to 18 months for a germinated seed to develop into a mature, flower bearing plant. Hibiscus flowers are capable of producing seeds. When pollen falls onto the flowers’ stigma a p od may form. Two months after pollination the pod will mature and expose its seeds. This process may need some coercing -- 60 to 80o F and high humidity. If the process is successful the resulting seeds may be gathered and planted. One must rem ember that the young plant will be a cross between both of its parents and may look very different from the plant on which the seed was obtained.

Tropical hibiscus can be propagated by stem cuttings. This method is very simple and effective. Take a 3-4" cutting off a healthy, mature hibiscus (the cutting should contain between 1and 4 nodes). Dip the basal end of the cutting into a rooting ho rmone containing 0.1% or 1000 ppm IBA. Then, plant the cutting in a light potting mix such as Sunshine Mix or PRO-MIX.

Propagation of hibiscus by leaf cuttings is similar to that of stem cuttings. The only difference between the two procedures is that in leaf cuttings, one leaf is dipped into the root hormone and planted instead of a whole stem.

Air layering is the fourth method of propagating hibiscus. To air layer, first select a healthy section of the plant. Make a slanting upward cut 1 ˝ inches long on one or both sides of the healthy stem about 3-12" from the stem tip. Insert IBA soak ed sphagnum moss under the wounded flap of tissue. Wrap black polyethylene plastic over the moss and fasten at both ends with twist-ties. Occasionally undo the top twist-tie to test the moisture in the sphagnum. It must be kept moist at all times, add wat er if necessary. When a substantial amount of roots develop remove the layer from the parent plant (Davies F. and R. Geneve).

The last method of propagating hibiscus is by grafting. Hybrid hibiscus are often grafted onto hardy rootstocks. A sharp knife is used to notch the rootstock and expose the cambium layer. A thin piece of the hybrid plant (containing a bud) is inser ted in the notch and the union is wrapped with grafting tape or a rubber strip (Tropical Hibiscus Propagation).

FUTURE WORK NEEDED

The only areas of the United States with climates conducive to tropical hibiscus growth are Florida and Hawaii. In the future, I hope there will be attempts to develop "tropical" hibiscus that can grow in non- tropical climates. Also, de veloping tropical hibiscus with larger flowers would be a great advancement for this crop. Hardy hibiscus develop "dinner plate" size flowers but they have dull, unattractive foliage. Combining the best traits of hardy hibiscus and tropical hibiscus could result in winter hardy plants, with shiny foliage with larger flowers.

REFERENCES

Davies F. and R. Geneve et. al. 1997. Plant Propagation: Principles and Practices.

Prentice Hall International, London.

Hibiscus Pruning, Fertilizer/Insect Control http://www.trop-hibiscus.com/bfertins.html

Tropical Hibiscus Propagation htpp://www.trop-hibiscus.com/cprop.html

Year round Hibiscus http://www.trop-hibiscus.com/gindr.html