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How do I overwinter my Chinese hibiscus?
How do I overwinter my Chinese hibiscus?
The Chinese hibiscus, or tropical hibiscus, has the botanical name Hibiscus rosa-sinensis. A shrub usually no more that 3' tall when grown in a pot, its 4"-8" flowers are open for only one day, but they may be produced in profusion and come in many colors - white, yellow, orange, red, pink - and ruffled or fringed, single or double.
In its native tropical habitat it blooms for most of the year, slowing down only in the cool, or dry, or wet season, as the case may be. In the Midwest, the seasonal climatic changes are much more extreme. While the Chinese hibiscus loves to be out in full sun in our hot and humid summer and will bloom profusely there, it must be brought in before first frost. How you handle it in the winter depends on your facilities.
If you have a greenhouse or a sunny garden room that is fairly warm, and your hibiscus can be in sun for several hours each day, you can keep it full-foliaged and blooming, at least to some degree, through the winter. The frequency of watering and fertilizing should be reduced from the summer maximum; the soil should continue to be kept evenly moist but not saturated, but the frequency of waterings to achieve this will be reduced as the plant's activity slows.
If you have no such facility, you can still keep your hibiscus alive for the next year. In September cease fertilizing and reduce water until the leaves begin to fall. Before frost, bring the plant in and place it in a cool place (not freezing) where it will get some light-it does not have to be sunlight or even bright light. Stored thus, you may allow the upper inch or two of soil to dry out; but water enough through the winter to keep the roots moist.
The next spring, when the weather has thoroughly warmed and there is no chance of another frost, it will have few or no leaves. Bring it out onto the terrace in the sun and prune it back as far as you wish. Resume the water and fertilizer and watch it grow and, in a few weeks, bloom-and even more profusely due to its pruning-back and dormant period.
Tropical hibiscus may be propagated from cuttings of new growth, using 3" shoots in water, moist sand, or vermiculite.
Insects occasionally infesting hibiscus include aphids, mites, whitefly, mealybug and scale. Wash off with a fine, hard spray of water; or, in the case of scale, wipe off with a cotton swab soaked in isopropyl alcohol. The only insecticide really needed is insecticidal soap. One spraying will probably suffice for all insects but scale, which will need several sprayings at weekly intervals.