How to Grow and Care for Hibiscus
About Hibiscus
Hibiscus (Hibiscus rosa-sinensis) grows 4 to 6 feet tall and is hardy in USDA zones 9 to 11. It grows best in full sun to part shade with medium water.
Hibiscus rosa-sinensis, Chinese hibiscus is a frost-tender broadleaved evergreen shrub that is native to tropical Asia and China. No wild populations of this plant have been found in modern times. It is winter hardy to USDA Zones 9-11. Hibiscus rosa-sinensis has been described as suffering from decline when temperatures drop below 60° F. It is best grown in full sun but it will tolerate partial shade. If grown in a container outside some protection from the late afternoon heat may be necessary. It may be placed into the garden landscape as an annual or can be grown in containers but must be brought into a warm sunny indoor location prior to a hard freeze. Chinese hibiscus feature glabrous, toothed, shiny green leaves up to 6 inches in length. The red flowers with 4-5 petals/rays are funnel-like measuring 4″-8″ in diameter with stamens in a showy central tube. In milder climates plants grown a rounded form 10-12′ tall. Plants grown in containers may be trimmed to 5′-6′ tall before being brought indoors. Plants that have been overwintered indoors will typically flower from spring to late summer. The flowers last for only one day. Chinese hibiscus may be utilized as large specimens, hedges, or screens in USDA zones 10-11. In areas where Chinese hibiscus is not winter hardy, they may be brought into a greenhouse or grown as a houseplant.When to Plant Hibiscus
Plant tropical hibiscus outdoors in spring once nighttime temperatures stay above 50°F. In zones colder than 9, grow it in a container and bring it indoors before frost.
How to Plant Hibiscus
Chinese hibiscus should be located in full sun planted in rich soil with significant proportions of organic matter and good drainage. If planted indoors it should be planted in suitably large containers with a “bright” light exposure. Propagation is most successful by utilizing stem cutting. Chinese hibiscus must not be confused with “Hardy Tropical Hibiscus” which has been developed to return year after year from the root system.
Hibiscus Care
The soil bed containing Chinese hibiscus should never be allowed to dry out especially in hot weather. Chinese hibiscus requires consistent watering and frequent grooming or cleaning away of the spent flowers which are generated on a daily basis. Properly shaped Chinese hibiscus should not require staking. If limbs grow disproportionately they may be trim back to reestablish balance in shape.
Fertilizing Hibiscus
Tropical hibiscus plants produce more blooms when they are given regular fertilization. The best fertilizers for use with hibiscus rosa-sinensis varieties have a reduced proportion of phosphorus. A slow-release fertilizer mix such as ’20-10-20′ with a smaller “middle” number is recommended in the winter if the plant is growing actively indoors. Liquid fertilizer with a higher middle number such as ’10-20-10′ has been advocated as a means of increasing flower production during the summer.
Pruning Hibiscus
Hibiscus require little pruning during the growing season unless they grow too large in which case it may be cut back as needed. The flowers last just one day. The removal of spent flowers is a daily necessity during the growing season. The plant should be pruned by one-half in early spring to maintain the desired shape and to encourage new growth. More frequent and lighter pruning may be needed throughout the year for Hibiscus grown indoors. The plants produce flowers on new wood, therefore pruning during the year will not stop flowering completely but it will delay it.
Hibiscus Pests and Diseases
With the help of beneficial insects and birds, healthy outdoor plants generally can avoid pest infestations. Aphids, thrips, and spider mites may occur which can be treated with a foliar spray utilizing Neem oil. As with all applications of insecticides, one should read the label completely and apply the neem oil spray when bees butterflies, and other beneficial insects are not near the plant. Insecticidal soaps have also been reported as successful it may be more challenging with large plants. Powdery or downy mildew and botrytis may attack the leaves. Fungicidal foliar sprays may be applied while prevention of leaf diseases is best achieved by avoiding watering the plant leaves directly or watering in the early morning to allow the leaves to dry by the effects of sunlight.
Is Hibiscus Toxic to Cats and Dogs?
PlantTAGG does not rate tropical hibiscus as pet-friendly. The ASPCA lists Hibiscus rosa-sinensis as non-toxic, but eating the leaves or flowers can still cause vomiting and diarrhea in dogs and cats. If you think a pet has eaten a toxic plant, call your veterinarian or the ASPCA Animal Poison Control Center at (888) 426-4435.
Hibiscus FAQs
Why are my hibiscus leaves turning yellow?
Yellow leaves usually point to watering problems, either too much or too little, or to a sudden change in light or temperature. Keep the soil evenly moist but never soggy.
How do I overwinter a hibiscus indoors?
Move it indoors before nights drop below 50°F, place it in your brightest window and water less often. Expect some leaf drop as it adjusts.
How long does a hibiscus flower last?
Each flower lasts about one day, but a healthy plant produces new blooms continuously from spring through fall.
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