Best known for its showy, plate-shaped flowers, hibiscus (Hibiscus) is a perennial shrub that can grow in most any region, depending on the variety. According to AboutHibiscus.com, these plants are among the most sought-after flowering plants by home gardeners. Hibiscus are relatively easy to care for, once established, and some varieties will bloom all summer.
Varieties of the hibiscus are the national flower of South Korea (H. syriacus) and Malaysia (H. rosa-sinensis). These plants produce a delicate, papery bloom.
Though hibiscus are usually associated with warm-weather areas, some varieties of this plant can survive to -10 degrees F. In fact, the Rose Mallow or Perennial Hibiscus (H. moscheutos), which has blooms of up to 12 inches, is among the most cold-hardy hibiscus.
But the Chinese or Tropical Hibiscus (H. rosa-sinensis), which is among the most popular varieties, thrives in warmer climates and is hardy to 30 degrees.
Light and Water
All hibiscus are sun-loving plants, though they can do well in light shade in the hottest, most humid regions. In general, hibiscus should be planted in full sun and protected from wind.
The water needs of hibiscus vary, though all varieties will thrive with regular water. Several varieties, including Rose of Sharon (H. syriacus), are somewhat drought tolerant.
Hibiscus need well-draining soil to thrive, and all varieties benefit from regular fertilizing. Low-phosphate and low-nitrogen fertilizers encourage blooms--too much nitrogen can result in prolific foliage and limited blooms. Hibiscus can be fertilized once a month.
Hibiscus thrive in neutral to slightly acidic soil with a pH between 6.0 and 7.0. Soil can be tested before planting, and, if it is alkaline (above 7.0) , sulfur can be added in the form of iron sulfate, aluminum sulfate, sphagnum peat or organic matter.
The size of the bloom on a hibiscus will vary depending on the variety. The Rose Mallow has the largest bloom (12 inches) while most other varieties have blooms ranging from 2 to 6 inches. Flowers can be single, semi-double or double, and are available in a rainbow of colors, ranging from pinks to purples to yellows to whites. Most hibiscus will flower beginning in early summer.
According to AboutHibiscus.com, red and yellow hibiscus blooms are the most popular.
Though hibiscus are relatively disease-free plants, they can be attacked by common garden pests, including aphids, scale, whiteflies and thirp. The Confederate Rose (H. mutabilis) is particularly susceptible to whiteflies.
A soapy mix of water and dishwashing soap can be used to eliminate aphids and whiteflies.