Rose Mallow

Rose mallow, also known as Chinese Hibiscus, belongs to the mallow family (Malvaceae). The original species Hibiscus rosa-sinensis likely originates from China, but Hibiscus is now found in almost all tropical and subtropical regions of the world. Hibiscus rosa-sinensis hybrids are particularly popular in the US: With magnificent flowers, they grace many a patio and balcony as potted plants in summer, and as houseplants, they bring tropical flair to your home.

Rose Mallow is mostly grown as a bushy small shrub or small tree in the United States. The original species can grow up to 10 feet tall when well cared for. The hybrids usually reach a height of 1.5 to 6.5 feet in pots. They are often treated with growth inhibitors that can lose their effect over time.

Chinese hibiscus leaves are glossy and dark green. They are elliptic and sometimes slightly split.

Rose Mallow flowers open between spring and fall, usually from March to October. They develop in the leaf axils and stand individually on long stems above the leaves. They have five very large petals, which together form a funnel shape. A column protrudes from the center with numerous stamens that grow together. Yellow stamens and red downy stigmas appear at the end. The flowers reach a size of 3.93 to 5.9 inches and glow in a vibrant red. The color spectrum of hybrids ranges from white, yellow and orange to pink and red, the flowers can be either single flower or double flower, and sometimes have a contrasting eye. The flowers wither quickly, but new buds appear all summer long.

After successful pollination, the Chinese Hibiscus adorns itself with capsules that can also persist on the plant through winter.

Rose Mallow likes very bright and sunny spots. It therefore likes being close to a sunny south facing window indoors or in a conservatory. In summer, the plant is happy outdoors in a warm location which is sheltered from the wind and rain. In summer, however, it should be protected from the intense midday sun both indoors and outdoors. Chinese hibiscus shows good growth at temperatures above 68 degrees Fahrenheit provided that it’s in a bright place. Temperatures between 61 and 65 degrees Fahrenheit are sufficient during the winter rest period (from around November to February). However, the thermometer should not drop below 57 degrees Fahrenheit.

A high quality potting soil or a similar mix - which is well-draining and rich in nutrients and humus - is a suitable substrate for Rose Mallow. The pH should ideally be in the neutral to slightly acidic range. Make sure that you choose a pot that drains well.

One of the most important tips when caring for Hibiscus: keep the substrate evenly fresh to moderately moist for Hibiscus rosa-sinensis hybrids. Long periods of dryness can cause bud drop. Rose Mallow needs to be watered almost daily in summer, but waterlogging must be avoided at all costs. Remove excess water from planters and saucers as soon as possible. You should also spray the plants with water from time to time. Watering can be reduced in fall, but the root ball should never be allowed to completely dry out.

During their growth phase, plants of the Mallow family not only need plenty of water, but also lots of nutrients. Between spring and fall, it is best to give the plants liquid fertilizer once a week during watering. Without a regular dose of nutrients, Rose Mallow will only form a small number of buds. There is no need to fertilize the plant during its winter resting period. You can start to gradually to fertilize it more in spring.

Young plants should be repotted in fresh soil each spring. Long shoots can be shortened prior to this. Older, larger Chinese hibiscus plants should be repotted every two to three years.

By pruning your Hibiscus regularly, you can encourage it to grow more branches and produce more flowers. You should slightly shorten the previous year’s shoots in spring so that young plants have nice, bushy growth. After a few years, when flowering gradually declines or the lower branches become very bare, it is advisable to prune the plant harder in spring. Shorten the shoots by about a half and thin out the plant as a whole. After a hard rejuvenation prune like this, the plant will generally not flower, but Hibiscus rosa-sinensis hybrids develop all the better for it the following year. Dead flowers should be removed on a regular basis.

Chinese Hibiscus is not hardy. To overwinter Hibiscus, move it into winter quarters in good time with temperatures between 61 and 65 degrees Fahrenheit, for example a moderately warm conservatory. It is advisable to do this as soon as nighttime temperatures drop below 54 degrees Fahrenheit. Check the flowering shrubs for pests before bringing them inside and remove any dead or wilted parts of the plant. In any case, winter quarters should be bright and slightly humid. It is perfectly normal for the shrub to drop a few leaves during the overwintering period. Water the plants sparingly during this time: the colder the room, the less often you need to use your watering can. From around March, you can put the potted plants in a brighter and warmer spot, give them more water and ventilate the room more often. You can put Hibiscus rosa-sinensis hybrids outdoors once the last late frost has passed. However, they should not be put in the blazing sun right away: to avoid sunburn, allow the plants to gradually get used to the new light conditions before moving them outside.

There is a vast range of Hibiscus rosa-sinensis varieties. The single-flowered varieties have proven to be slightly more robust. Here is a small selection:

• ‘Apollo’ adorns itself with two-tone yellow and red flowers.
• ‘Bridal Veil’ develops pristine white, crimped flowers.
• ‘Cooperi’ has relatively small red flowers. Its leaves are quite narrow, heavily blotched white with pink to red speckles. This variety is slightly more demanding than the species itself in terms of temperature and humidity.
• ‘Hula Girl’ develops large yellow flowers with a red center.
• The flowers of ‘Fiesta’ have an intense yellow-orange glow with a pink eye.
• ‘The President’ develops large flowers with a soft violet pink color.

There are several ways to successfully propagate Hibiscus. It is best to propagate Chinese Hibiscus in spring or summer from semi-hardwood tip or stem cuttings. The cuttings take root in standard potting soil at a ground temperature of 72 degrees Fahrenheit.

Dry, heated air can lead to infestations of spider mites and aphids. Newly acquired plants are notorious for bud drop. This can be caused by changing conditions or the root ball drying out. So make sure the plant has a light, airy location and sufficient water.