It's never too hot for hibiscus

Here's a colorful plant that continues looking good through the dog days of August

Bright as a parrot's feathers, the bold colors of hibiscus blossoms are a match for the jungle-like heat and humidity of late summer. Lasting only one day, their exotic scarlet, deep-pink, flame-orange, or citrus-yellow blooms unfurl to catch the eye and lure one to linger with hummingbirds and butterflies at the garden's edge.

The rich genetic makeup of tropical Hibiscus rosa-sinensis - also known as Chinese hibiscus - and the hardy perennial Hibiscus moscheutos (also known as rose-mallow) have enticed hybridizers to produce a diverse parade of variegated foliage, double and single blossoms, and unique color blends.

Sizes range from potted tender tropicals with two- to eight-inch-diameter flowers, to buxom perennial landscape "shrubs" such as Lord Baltimore, Southern Belle, and Blue River, whose blossoms are eight to 10 inches across, on plants that range from 20 inches to 8 feet tall. Moy Grande bears dinner-plate-size open-faced fuchsia blooms, each up to 12 inches across.

While many cultivars of both tropical and perennial hibiscus produce flamboyant flowers, others recall the cool iridescence of rain-forest butterflies. These blossoms contrast with summer's relentless heat in shades of orchid, cream, blue, and magenta.

Blue Moon, a Brazilian cultivar, and the sapphire overtones of Midnight Blue, Santa Cruz, and Monterey Bay all exemplify the quest for a true-blue tropical hibiscus.

Whether in the garden, at poolside, or indoors, these members of the Malvaceae family impart an atmosphere of tropical ease.

Hibiscus rosa-sinensis is Hawaii's state flower, and reaches 30 feet tall in the tropics. Plants rarely grow taller than 15 feet in the continental US, however, even in the mildest parts of California.

Rose-mallow, which is native to the swamps of Louisiana and other Gulf Coast states, has been a heat-loving staple of Southern gardens for many years.

As cut flowers, perennial hardy types retain their color and shape for several hours without water.

For an elegant place setting (or for gift packages or hair decorations), simply clip blooms in the morning, store them without water in the refrigerator, and accent the dining table with them in the evening.

"Perennial hibiscus is the only flower of its size in the world that will not wilt when displayed out of water for such a long period of time," says Jerry Parsons, extension horticulturist with Texas A&M University. "It's a perfect flower to take to hospitals or convalescents."

But, he adds, gardeners should remember that tropical hibiscus flowers do not possess these traits.

At the nursery, choose the species that's right for your situation. Both tropical and hardy, hibiscus crave nearly full sun, ample water, and well-drained rich soil. Tropical specimens do fine outdoors in a sunny spot during summer, but they must move indoors during cold weather. Or, use them as annuals, planting fresh specimens each spring.

Perennial hibiscus, once established, can overwinter outdoors in USDA hardiness Zone 5 and southward. Simply trim back the plants in fall and keep them well mulched and watered.

How do you tell the difference between tropical and perennial hibiscus? Tropical hibiscus has glossy, deep-green leaves. Perennial hibiscus leaves usually have a bright green matte finish, and resemble maple leaves.

Over the past several years, hybridizers have been producing variations of reliably hardy hibiscus to fill the increasing demand for large-size, easy-care, pest-resistant perennials with outstanding flowers.

Hummingbirds and butterflies appreciate those efforts, especially when gardeners plant groupings of bright red- or orange-flowered hibiscus.

Both tropical and perennial hibiscus will thrive and develop lush foliage and abundant blooms when planted in soil or In containers. They'll provide luxuriant blooms until the first frost.

Depending on your climate, you can use either or both types as a screen, backdrop, or small tree. Dress up a picnic table with a potted hibiscus, or you might even want to bring a container-grown hibiscus indoors for a short time to dress up the dinner table.

Place container specimens with other heat-loving flowering plants such as bougainvillea, coral vine, purslane, Cuphea (Mexican heather and cigar plant), and Mandevilla.

Even this late in the season, you may be able to find both tropical and hardy perennial hibiscus plants at your local nursery.

As summer wears you down, they'll rally under the brightest, hottest sunlight.

How to care for hibiscus

Tropical hibiscus (Hibiscus rosa-sinensis)

Plant in well-drained soil or raised beds and containers. May also be grown in a sunny spot indoors, as a houseplant.

Protect plants from frost and wind, especially ocean wind.

In warm inland areas, protect plants from hot afternoon sun.

If buds fall off before opening, move the plant to a brighter place.

Buds form on new shoots, and plants need nitrogen to promote that growth. Use a water-soluble, high-nitrogen plant food each time you water.

Remove faded blossoms to encourage reblooming.

Water deeply and frequently, and treat for aphids if needed.

Prune mature plants in early spring, removing about one-third of old wood. This will keep the plants vigorous. To increase flower production, pinch tips of stems in spring and summer.

Hardy (perennial) hibiscus (Hibiscus moscheutos)

Rich, moist, well-drained soil, along with full sun, encourages vigorous growth; however, plants will also tolerate light shade and less- desirable soils.

Water regularly and deeply. A 2-inch-deep mulch on top of the soil helps conserve moisture.

Apply a pelleted timed-release fertilizer to the soil every six to eight weeks through the summer. Use a water-soluble fertilizer weekly from April through August. Don't fertilize after summer ends, to allow the plant to "harden off" and slow its growth going into winter. This prevents damage that occurs when a plant is actively growing when severely cold weather arrives.

Japanese beetles are attracted to perennial hibiscus and may need to be controlled. If leaf-eating caterpillars are a problem, use products containing Bacillus thuringiensis (Bt), an organic control.

Remove spent flowers and seedpods to encourage reblooming.

Protect plants from strong winds to prevent stem breakage. If main canes break during the growing season, remove them and allow side shoots to sprout.

In winter, move containers indoors or to a protected location when temperatures threaten to fall below 15 degrees F.

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