The hibiscus is widely grown in tropical and subtropical regions. Native to China, the hibiscus shrub grows to a height of 15 feet and a spread of 8 feet depending on the variety or cultivar. Flowers range in size from 8 to 10 inches across. They appear trumpet-shaped in shades of red, orange, yellow, salmon and pink. The blossoms last less then a day on most varieties. The foliage is deep green and abundant year-long.
Hibiscus shrubs grow in a wide range of soil. A pH of 5.5 to 6.5 is ideal. The shrub prefers full sunlight but numerous varieties will tolerate partial shade without flower reduction. Hibiscus is highly tolerant of salt spray and grows well in ocean-side locations.
In tropical regions the hibiscus grows as an evergreen with year-round blossoming. In subtropical locations the shrub is often killed to the ground in a heavy frost or freeze but eventually will return on its root system if the cold snap is of short duration. Most hibiscus varieties cannot withstand temperatures that dip below 28 to 30 degrees F.
The hibiscus enjoys moist soil conditions. Keep the soil moist to a depth of 18 inches around the hibiscus. If the shrub becomes too dry it will begin to wilt. Apply a 2- to 3-inch layer of mulch around the base of the shrub to help keep the soil moist during the extreme heat of the summer. Keep the mulch at least 2 inches from shrub's base.
Fertilize the hibiscus once per month. Apply 1 lb. of 15-5-15 fertilizer around the base of a full-grown hibiscus shrub. Follow the directions on the label for application instructions. Water the fertilizer fully into the soil. The hibiscus also benefits from foliar micro-nutrient sprays applied three times per year.
Prune the hibiscus in the spring to maintain its size and shape. Flowers are produced on new growth so remove old, damaged or diseased branches. Thinning out the hibiscus shrub allows air flow and helps prevent fungal diseases.
The hibiscus is propagated using seed or softwood cuttings. Cuttings easily root within six weeks and produce a shrub that flowers in approximately nine months, according to the University of Florida. The hibiscus is also propagated through air layering and by grafting or budding. Grafting and budding are rarely used except on a few varieties that are susceptible to nematodes or produce weak plants.