The hibiscus is an elegant blooming plant whose popularity is growing, whether container cultivated around decks, porches, and patios or used in landscape settings as annual color.
While individual flowers may last only a day or so, especially in the hot summer, many new buds form daily for a spectacular flower show from spring through fall.
The Hibiscus in Europe & the USA
First classified by Linnaeus in Species Pantarum (1753) as “Hibiscus rosa-sinensis”, the hibiscus cited was probably the double red, which was common throughout China, India, South-East Asia, and the Pacific Islands. While the double red had been known since the 1600s, only after Linnaeus made his first observations did a single red form of the hibiscus appear in written descriptions. Singles were considered rare during these early days until they were introduced into Europe from the South Indian Ocean.
By the 19th century, the hibiscus had made its way into European greenhouses, as other forms were discovered and early hibiscus gardeners made cultivars. Most early forms originated from Asia and the South Pacific. Still, as early as 1820, Charles Telfair began crossing the Mauritius island native Hibiscus Liliiflorus with older forms of Hibiscus rosa-sinensis. By 1900, hybridizing had begun in Hawaii, India, Ceylon, Fiji, and Florida.
Gardeners can now choose from hundreds of hibiscus varieties, with more varieties introduced yearly. The glossy green hibiscus foliage varies considerably in size and texture, and the flower’s colors seemingly have no limits. We now have brown, green, gray, and maroon hibiscus, as well as violet, red, orange, yellow and pink, and white. Many hibiscus have multi-color combinations. Size ranges from 2- to 3-inch miniatures to the dinner plate size of the mallow or Hibiscus Moscheutos varieties.
One of the drawbacks of hibiscus in arrangements is that the flowers last only one day, especially during the summer. Nevertheless, hibiscus remains popular for decoration since flowers needn’t be placed in water to prevent wilting.
For an evening party, try this tip: Pick hibiscus blooms in the morning, just as they are opening, and place them in a sealed plastic bag. Refrigerate them until one or two hours before displaying them. Then remove them from the bag and let them open on their own. Now they will last all evening!
A healthy, well-fertilized plant is more resistant to insects and diseases. Growers who take good care of their hibiscus experience few problems. Feed your hibiscus according to the label instructions of the fertilizer you select.
Hibiscus fertilizer is formulated with all the plant food elements for successful cultivation. The low phosphate content provides enough phosphorus for bloom but doesn’t have the excess phosphorus that would tie up trace elements like magnesium. The potassium is derived from the nitrate of potash, which lacks the chlorides harmful to hibiscus.
Be aware of your fertilizer ingredients. Most general fertilizers use the less expensive muriate of potash, which is high in chlorides. Proper fertilizer is essential to container-grown hibiscus, as fluids move through the confined soil mix and aren’t dissipated.
Feed your plant when it is dry or just moist. Always water the plant first, then fertilize. Water again if you apply dry fertilizer. It’s best to feed plants at cooler times of the day. Morning is ideal. Remember, the more you water in hot weather, the more you may have to fertilize.
Insects & Disease
With its lush tropical foliage, hibiscus in your yard can offer a tempting meal for hungry insects. To control cabbage loopers, cutworms and other worms, use a bacterial insecticide. For aphids, whiteflies, scales, mealy bugs, and thrips, use a systemic insecticide that moves up the plant to control pests on both foliage and flowers. If you’re not sure what type of insects you have, take a sample (or photo) to your local Anawalt Garden Center for proper identification.
For fungal problems, use a fungicide according to label instructions. Botrytis is the most common disease, and it shows up as grey fuzzy spots on flowers and foliage. Some varieties are more resistant than others to certain diseases.
Hibiscus responds well to pruning, especially during the mild winter months in Southern California. The pruning technique you use depends on where your hibiscus size and where it’s planted. For a large shrub, trim off only one-third of the growth each year, cutting just above an outward-facing bud. You can prune smaller hibiscus back more severely, as the plant will reward you with vigorous new growth.
Prune light and often, rather than drastically cutting back a plant all at once. If you’re unsure of your skills or the size of pruning needed, talk to your Anawalt Garden Center professional.
Protection Against Frost
Cover your hibiscus plants when temperatures are expected to drop below 32 degrees or when there is a danger of frost.
Hibiscus planted in the ground: Before the first freeze, cut the hibiscus bush back to 4 to 6 inches above ground level. Cover hibiscus completely with pine needle mulch to give your plants a chance to survive a mild winter. In the spring, after the danger of freezing has passed, rake mulch away from the trunk to allow plants to sprout freely.
Containerized hibiscus: Prune to shape in late January or February to assure ample spring blooms, as hibiscus blooms on new wood. Prune to shape or control the size of the plant at any time.
Plant Your Hibiscus Right!
Plant your hibiscus in a sunny location (at least 6 hours per day). Prepare the bed for good drainage. Blend approximately 14 bags of azalea planting mix per 100 sq ft of existing soil. Add the appropriate amount (according to instructions) of hibiscus fertilizer. A pre-emergent herbicide will prevent most weeds from germinating, and pine bark mulch will insulate the roots, retain moisture, and also help control weeds.
Hibiscus planted in a raised bed
If planting hibiscus in a pot, we recommend that any container be at least 14 inches in diameter, with holes in the bottom for drainage. Use cracked pottery to cover the hole, but still allow adequate water drainage. Fill with blooming tropical soil mix blended with the appropriate amount of hibiscus fertilizer.
Hibiscus planted in a pot
Fertilize every 2 to 4 weeks with hibiscus fertilizer. Hibiscus prefers moist soil when growing; for the best bloom production, use warm (not cold) water to irrigate your plant.
Monitor your hibiscus for signs of nutrient deficiency or overwatering. Yellow foliage and wilting stems are likely signs of an underlying problem. If you’re worried, ask an Anawalt Garden Center professional for advice. With the right care and attention, your hibiscus can thrive and provide beautiful blooms throughout the growing season.