Hibiscus flowers, whether tropical or temperate, generally only bloom for a day — opening in the morning, closing at nightfall, and ready to deadhead the following day. Still, when you know how to grow hibiscus, you'll be rewarded by a profusion of blooms that continues for weeks!
All in all, there are over 200 varieties of hibiscus, ranging from tropical annuals to temperate varieties (hardy perennials). Unfortunately, garden centers and many nurseries sell them under one category, "hibiscus". However, you can easily distinguish the two types by differences in both their flowers and foliage.
Although some cultivars of hibiscus tolerate partial shade, the hibiscus is a typical sun-lover. However, one thing your hibiscus won't tolerate is drought! From the same plant family as the marsh mallow, hibiscus carries on the family tradition of needing lots of water. In particular, your container-grown tropical hibiscus may need a daily drink to thrive. Dropping flower buds, leaves, or yellowing of foliage are each signs that your hibiscus isn't getting enough water. Some tropical hibiscus cultivars can even withstand flooding.
Tropical hibiscus usually has dark green, glossy leaves with either single or double blooms of three to four inches. Tropical hibiscus blooms in colors of yellow, orange, pink or red.
Tropical hibiscus won't tolerate frost. Even a couple of nights below freezing spells the end of it. When temperatures begin to dip, it's time to move your tropical hibiscus indoors. In the spring, gardeners often acclimate or "harden off" young transplants setting them outdoors for a few hours each day and increasing the time as the days grow warmer. In the autumn, reversing this process with your tropical hibiscus helps it adjust to the change from living outside to going indoors for the winter.
Temperate hibiscus leaves are heart shaped, rough textured, and medium green. Single blooms span up to eight inches in diameter and span the red color range from white to pink to maroon.
Despite a preference for lots of sunlight and nutrient-rich organic soil, the perennial hibiscus has been found growing wild in vacant lots and shady areas of southern zones. However, a regular water supply is critical to achieve the profuse bloom that is the goal of many perennial hibiscus growers.
Taken from the stem, flowers can be displayed out of water up to a full day. The flowers of the perennial hibiscus are the only blooms of this size that can survive out of water without wilting for extended periods.
Perennial seed from the hardy hibiscus delivers a 50% germination rate in two to four weeks if sowed immediately after harvest. However, if over-wintered at 40 degrees Fahrenheit, perennial hibiscus seed can be sown directly into the spring garden.
The perennial hibiscus is "root hardy"; although it dies to the ground in the fall, it sprouts from its roots again in the spring. Because it's a "late bloomer", growers often mistakenly think the still-dormant plant is dead and are surprised by new growth about the time they are ready to replace it! This is also frequently the case when purchasing bare-root transplants. Whether planting a transplant or waiting for the rebirth of your temperate hibiscus in spring, remember, if canes are flexible give the plant time and it will reward you with prolific bloom.
Although the temperate hibiscus takes its name from "hibiskos", which is the old Greek word for the common marsh mallow and is commonly called "rose mallow" it actually isn't a marsh mallow at all. As well as blooming with lovely flowers, temperate hibiscus is also an herb that comes from a family of other useful plants that includes cotton, hollyhock, and okra. A commonly grown temperate hibiscus is the Rose of Sharon.
In ancient Egypt, the flowers from these perennial herbs were believed to be an aphrodisiac. Because of this belief, Egyptian women were forbidden to drink hibiscus tea. Today, we throw caution to the wind and mix perennial hibiscus leaves, flowers, and seeds to put the "zing" into our red zinger tea!