For the Love of Double Tropical Hibiscus
Hibiscus is an ornamental plant commonly grown in the temperate, subtropical, or tropical regions around the world.
A hibiscus flower usually has five petals. Thanks to modern cultivation techniques, some varieties can produce flowers with more than five petals – called “double hibiscus” – in a dazzling array of colors, sizes, and shapes!
Because of the unusual number of petals, a double hibiscus blossom looks more impressive and fascinating than its cousin the ordinary five-petal hibiscus!
Different types of hibiscus
Hibiscus belongs to the mallow (Malvaceae) family. Generally, there are two categories of hibiscus: tropical and hardy.
Tropical hibiscus (Hibiscus rosa-sinensis) prefers a sunny, warm, humid climate and cannot tolerate cold temperatures. This popular hibiscus species has been widely cultivated and hybridized into hundreds of varieties! A majority of double hibiscus belongs to this tropical category.
Hardy hibiscus (Hibiscus syriacus) tolerates cold or even freezing temperatures. Also known as rose mallow or rose of Sharon, this hibiscus species is a tough herbaceous perennial! The plants often die back to the ground in winter then regrow when warmer spring weather returns. Very few hardy hibiscus produce double blooms.
Note: This article devotes to the double tropical hibiscus type. The photos were taken at the author’s garden located in the lower Puna district (USDA Plant Hardiness Zone 12b) and other locations on the Big Island of Hawaii.
Did you know
Okra (yes, the humble pod vegetable used in the famous Southern stew gumbo) is in the same Malvaceae family and closely related to the hibiscus. An okra blossom looks very similar to a five-petal hibiscus flower, usually in pale yellow color.
How to grow double tropical hibiscus
You may grow double tropical hibiscus from stem cuttings or seeds. However, with these 2 methods, it will take years for the plant to mature and produce its first bloom!
The quickest way to have a double tropical hibiscus in your garden is to buy a potted plant from your local garden center or nursery. Potted plants for sale are 3-4 years old and most likely already in bloom, you can easily pick out your favorite flower color!
You may plant double tropical hibiscus in the ground or in a container, depends on where you live.
How to care for double tropical hibiscus
In the ground: If you live in a warm climate, plant your double tropical hibiscus directly in the ground. It needs a full-sun location to thrive. It also prefers well-drain and acidic soils (pH 5.5 or less). Water the plant regularly, especially when there is no rain! If the plant doesn’t get adequate water, its leaves will turn yellow and drop off. All flower buds will also fall off.
Double tropical hibiscus is a heavy feeder, it needs fertilizer to produce beautiful blooms. You may use any commercial hibiscus fertilizer (liquid or granule) and follow the directions on how often to apply (weekly, monthly, etc.). As a rule of thumb, a younger plant will require regular feeding for vigorous growth. Well-established plant only needs fertilizer once or twice a year. Adding organic compost and mulch will also improve soil condition and promote healthy root growth.
Some double tropical hibiscus planted in the ground can grow into a large shrub 12-15 feet tall. Yearly pruning/trimming will keep the plant at desirable height and shape. Prune the plant in early spring before any new growth appears. Regular trimming will also make the plant bushy and more compact.
In a container: If you live in an area with cold/freezing winter weather, planting a double tropical hibiscus in a container is your best option. Enjoy the plant and its gorgeous blooms on the patio or deck during the warm season, then move it indoors for protection before the first frost arrives.
Use a well-drained potting mix (with compost and perlite) when planting your plant in a container. Make sure the container has drainage holes in the bottom to prevent root rot caused by excess water. As much as it loves humidity and regular watering, double tropical hibiscus does not like wet, soggy feet!
Water the potted plant twice a day when it is hot and dry. You can tell your plant is thirsty when its leaves and flowers are wilting. Feed the plant with a fertilizer (contains high potassium) formulated for potted flowering plants to encourage non-stop blooming.
It takes some extra care to winterize a double tropical hibiscus indoors. Be sure to place the container near a well-insulated window, the plant should receive at least 6 hours of sunlight and no chilly draft! Use a spray bottle to mist the plant once a week to help it cope with the dry, hot air indoors. (This also prevents spider mites from attacking the plant!) And finally, water it sparingly (soil is slightly moist to the touch) as the plant is taking a break from growing!
Did you know
Native Hawaiian yellow hibiscus (Hibiscus brackenridgei) is the official State Flower of Hawaii. Also known as pua aloalo or ma’o hau hele in the Hawaiian language, it is quite rare and considered to be an endangered species.
Enjoy your double tropical hibiscus
With proper care and ideal growing conditions, your double tropical hibiscus will reward you with spectacular blooms and transform your garden into a little exotic tropical paradise.
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
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© 2019 Viet Doan