The tropical hibiscus flower, or Chinese hibiscus (Hibiscus rosa sinensis), unfurls large colorful blossoms during summertime. While Chinese hibiscus are not suited for outdoor growth in most areas, gardeners can care for the plant as an annual or can winter the plant indoors. Although these plants are not cold hardy they are relatively unfussy in terms of other care requirements and add lots of color to a garden.
Chinese hibiscus can only be grown outdoors in hardiness zones 9 and 10. Certain cultivars of this flower are more sensitive than others. Growers in other regions can keep Chinese hibiscus but must move the plants indoors during winter to keep them alive. The San Antonio Express News notes that even southern Texas experiences cold enough temperatures at times to harm this plant, and suggests growing it in a container so gardeners in zones 9 and 10 can move the hibiscus indoors in cold spells.
Chinese hibiscus flowers need full sun to grow, but in hot spells shade will protect the flowers. Excess sun can lead the plant to produce fewer (and smaller) blossoms. Provide plants with shade for a couple hours daily to enjoy the largest blossoms, according to the University of Illinois Extension.
Hibiscus require regular watering but excess water can damage the plant. Water the hibiscus until the soil becomes saturated with water, then wait until the soil dries out to water again. To test the moisture of the soil, stick one finger a couple inches down into the soil. If this feels wet, hold off on watering.
When growing hibiscus in containers, choose those with drainage holes to prevent the plant from getting root rot due to waterlogged soil.
Hibiscus flowers can be grown either in the ground or in a container. Container hibiscus should always be used in cold areas where the plant cannot overwinter. Growers who move the plant indoors for the winter need to slowly re-introduce their hibiscus to sunlight in the spring to avoid frying the plant. Keep the plant outdoors in shade, then place it in sun for a couple of hours. Increase the sun exposure over the course of a few weeks until the plant can be in sun all day.
Hibiscus benefit from annual pruning in the early spring. Chinese hibiscus flower on new growth rather than old, so gardeners can prune out old woody stems using anvil pruners. Never prune more than 1/3 of the old growth per year.