© Janet Davis

 

For many indoor gardeners, the most satisfying of all flowering houseplants is a healthy, happy hibiscus.  Hibiscus plants flower indoors from late spring to fall, and outdoors in summer.  Indoors, it does best in a bright, south-facing window, a little back from the glass or in filtered light to prevent leaf burn; outdoors, it needs a sunny, but protected spot.

 

When flower buds appear, be very cautious about moving your plant around.  Hibiscus is extremely sensitive to a change in the direction of light, and will drop its buds in protest.  Fertilize your hibiscus plant once a month in spring and summer with a balanced fertilizer, such as 20-20-20, and once every 2 months in winter.

 

During the growing season, hibiscus plants need to be kept adequately moist, at 50-60% humidity; drooping leaves are a sign that that the plant is thirsty.  If your hibiscus spent the summer outdoors and flowered well there, it needs to rest in winter, so water it sparingly (but don’t let it dry out completely) and keep it on the cool side, with night temperatures of 10-17C (50-60F).  In late winter, or early spring, prune it back to a compact shape. 

 

Many people buy a “dwarf” hibiscus plant loaded with buds as a houseplant, and assume that’s what the plant will look like forever, then are shocked to find 6 months later that Little Red Riding Hood has turned into Shaq O’Neill as branches reach toward the ceiling. What happened?  Answer:  The grower has sprayed the plant several times with a growth retardant to initiate budding and keep the plant compact.  However, the effect of growth-regulating hormones wears off after several months to a year.  Left unpruned, a hibiscus can quickly reach 8-10 feet with all the flowers on top.

 

Hibiscus plants indoors are often plagued with aphids, spider mites and, especially, whiteflies.  Applications of insecticidal soap spray, either purchased or homemade by mixing 1 tablespoon of liquid dish soap with 1 quart of water, can be tried.  Make sure you spray the underside of the leaves, and re-spray after 4 days if problems persist

 

Hibiscus (Hibiscus rosa-sinensis) or “rose of China” is a woody shrub native to tropical Asia, specifically south China.  But it is widely planted throughout the Caribbean, Mexico and other warm places, and is the state flower of Hawaii, as well as the national flower of a few Caribbean nations.  In the wild, hibiscus has single red flwors and grows to about 30 feet. Two popular hardy plants in the same genus include the August blooming shrub rose-of-sharon (Hibiscus syriacus) and the moisture-loving perennial swamp mallow (Hibiscus moscheutos). 

 

Tropical hibiscus blossoms are single or double, and hybridizers have worked overtime to produce a rainbow of colors, fromwhite through cream, yellow, peach, orange, scarlet, pink, lavender-blue and many bi-tones.  Flowers are produced on new growth.  Individual blooms last only one day.

 

If you’re a real hibiscus nut and would like to communicate with others out there just like you, consider joining the American Hibiscus Society.

 

Adapted from a column that appeared originally in the Toronto Sun

 

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