Rose of Sharon (Hibiscus syriacus)

Hibiscus, Rose of China, Rose of Sharon, Rose-of-Sharon, Shrub Althea

If you’re looking to beautify your garden by adding a dash of colour to it, planting Hibiscus Syriacus can prove to be a great idea. These beautiful and exotic plants are available in a variety of vibrant shades, making them the perfect addition for enhancing your garden’s visual appeal. Moreover, they are extremely easy to grow and maintain. So, read on to know more about the benefits and uses of Hibiscus Syriacus as well as the best way to grow and care for them. 

I. Appearance and Characteristics 

Hibiscus syriacus is a species of flowering plant in the mallow family, Malvaceae. It is native to areas of east Asia, but widely introduced elsewhere, including much of Europe and North America. It was given the epithet syriacus because it had been collected from gardens in Syria. Common names include the rose of Sharon, (especially in North America), Syrian ketmia, shrub althea (or simply althea), and rose mallow (in the United Kingdom). It is the national flower of South Korea and is mentioned in the South Korean national anthem.

Hibiscus syriacus is a hardy deciduous shrub. It is upright and vase-shaped, reaching 2–4 m (7–13 feet) in height, bearing large trumpet-shaped flowers with prominent yellow-tipped white stamens. The flowers are often pink in color, but can also be dark pink (almost purple), light pink or white. Individual flowers are short-lived, lasting only a day. However, numerous buds produced on the shrub’s new growth provide prolific flowering over a long summer blooming period. The soil in which the Hibiscus thrives on is moist but well-drained, and organically rich. Hibiscus syriacus is highly tolerant of air pollution, heat, humidity, poor soil and drought. The species has naturalized very well in many suburban areas and might even be termed slightly invasive, so frequently does it seed.

Growth

The branches are thin and gray, white-lenticeled, with raised leaf scars and small buds. Stems and branches do not branch very much unless pruned, resulting in many long, straight stems that originate from about 1.5–4 cm (0.5–1.5 inches) above the ground, giving rise to the shrub’s overall vase shape. The leaves appear unusually late in the season, in May. They are usually green or yellowish green, alternate, broadly ovate, palmately veined, and 7.5 cm (3 inches) long. They have three distinct lobes with coarsely-toothed margins.

Flowers

Hibiscus syriacus has 5-petaled flowers (to 7.5 cm or 3 inches diameter) in solid colors of white, red, purple, mauve, violet, or blue, or bicolors with a different colored throat, depending upon the cultivar. Extending from the base of these five petals is the pistil at the center, with the stamen around it. These basic characteristics give the H. syriacus flower and its many variants their distinctive form. The plant can bloom continuously from July through September, usually at night. With maturity, flexible plant stems become weighted under the load of prolific summer flowers, and bend over halfway to the ground.

Fruits and seeds

Most modern cultivars are virtually fruitless. The fruits of those that have them are green or brown, ornamentally unattractive 5-valved dehiscent capsules, which persist throughout much of the winter on older cultivars. They will eventually shatter over the course of the dormant season and spread their easily germinating seeds around the base of the parent plant, forming colonies with time.

II. How to Grow and Care

Sunlight

Full sun, or at least six to eight hours of direct sunlight most days, is what Rose of Sharon prefers. However, Hibiscus Syriacus can also thrive in some shade. However, excessive shadow can reduce flowering and promote illnesses like fungus.

Humidity and temperature 

Even though Hibiscus Syriacus enjoy the heat, they can also endure winters with below-freezing temperatures of up to -20 degrees Fahrenheit. If the air is circulated properly, it can even withstand excessive humidity. In contrast, moist environments can encourage the growth of fungi.

Watering

Once established, Rose of Sharon is able to withstand drought, though it won’t bloom profusely if it lacks water. Young plants need more frequent watering until they become established. Water your Rose of Sharon thoroughly when the top few inches of soil feel dry. If possible, use distilled water or rainwater, as this type of hibiscus is sensitive to salts and minerals present in the water.

Soil

Various soil types, including loamy, sandy, and clay soils, are suitable for this shrub’s growth. Hibiscus Syriacus can handle slightly alkaline soil but prefers one that is nutrient-rich, well-draining, and between slightly acidic and neutral in pH.

Fertilizing

Rose of Sharon should be fertilized once a year, in spring. Use a slow-release, general-purpose fertilizer or apply fertilizer specifically formulated for hibiscus plants. Do not over-fertilize. If you notice any signs of nutrient deficiency, apply additional fertilizer accordingly.

Pruning

This shrub grows naturally in an attractive form, so it doesn’t need much pruning. But you can tidy up its growth each year to maintain the size and shape you desire. Rose of Sharon blooms on new wood, so it should be pruned in the late winter or early spring to avoid cutting off any flower buds later in the season. Pruning back stem tips will encourage more branching and thus more flowers. Remove any damaged or diseased branches as they arise.

Additionally, some the self-seeding rose of Sharon can become messy as they spread seeds, however, you can mitigate this issue by deadheading the seed pods as they develop. This will also help address its invasive nature

Propagation

The best way to propagate this shrub is by stem cuttings. Not only is this an inexpensive way to generate a new plant, but it also allows you to continue the lineage of a variety whose flowers you especially like. The best time to take cuttings is in midsummer. Here’s how:

  • Cut a pencil-wide stem that’s 4″ to 6″ long. Remove the leaves from the bottom half of the stem.
  • Dip the cut end of the stem into the rooting hormone.
  • Plant the bottom third to bottom half of the stem in a small container filled with soilless potting mix. Make sure the container has drainage holes.
  • Water to lightly moisten the growing medium.
  • Place a clear plastic bag over the container.
  • Put the container in a warm spot with bright indirect light.
  • Check the growing medium every few days to make sure it remains moist. Add more water if necessary, but don’t let it get soggy.
  • Remove the plastic bag after 7 days.
  • Check for roots in 1 to 2 months. Pull gently on the stem; if you feel resistance, the stem has rooted. New leaf growth is also a sign the stem has rooted.
  • Wait for at least two inches of stem growth before planting it in your garden.

Potting and Repotting 

If you are potting or repotting a rose of Sharon, make sure to do it when temperatures are warmer, ideally in the spring or fall. Avoid going too large and choose a pot that is one to three inches larger than your plant’s roots. Rose of Sharon prefers well-draining soil, so opt for a container with drainage holes and choose a high-quality potting mix. As the plant grows, you can upgrade to a larger container or prune the roots.

Overwintering

Rose of Sharon doesn’t typically need any special winter care in its hardiness zones. Ideally, it should be situated in a spot that’s protected from strong, chilling, drying winds. If you live in a cold part of its hardiness zones, adding a layer of mulch around its roots also can help to insulate the shrub from extreme weather.

Pests and Diseases

Common Pests

The chief pest problem for this shrub is the Japanese beetle. Japanese beetles are somewhat easier to control than many other insect pests because their large size makes them noticeable. That means you’ll likely spot them before they’ve done a lot of damage to your plant. The easiest way to kill them is to pick or shake them off the plant by hand and drop them into a container filled with soapy water. The insect breathes through its skin, so a coating of soap over its body effectively suffocates it.

Common Problems

This shrub is generally robust in its preferred environment. However, inadequate conditions can cause some common issues to arise.

Leaves Turning Yellow

Overwatering is often the culprit when your shrub’s leaves start to turn yellow. Make sure your shrub is planted in soil with sharp drainage and that it’s never in waterlogged conditions. It might be necessary to move your shrub if it’s located in a poorly drained spot.

Flower Buds and Leaves Dropping

Flower buds and leaves dropping from the rose of Sharon is most likely caused by stress, which can be the result of too little or too much moisture.

Browning Leaves

Similar to leaves dropping, browning leaves are likely caused by stress, which could be the result of poor drainage resulting in too much moisture in the soil.

Wilted Leaves

Wilted leaves could be caused by stress due to repotting rose of Sharon. This may impact the plant for several years and pruning dead leaves can help alleviate the issue.

Stunted Growth

Rose of Sharon needs full sun, so if it’s receiving too much shade that could impact both its growth rate and its blooms.

III. Uses and Benefits 

National flower

Hibiscus syriacus, also known as the Korean rose, is the national flower of South Korea. The flower appears in national emblems, and Korea is compared poetically to the flower in the South Korean national anthem. The flower’s name in Korean is mugunghwa (Hangul: 무궁화; Hanja: 無窮花) or mokkeunhwa (Hangul: 목근화; Hanja: 木槿花). The flower’s symbolic significance stems from the Korean word mugung, which means “eternity” or “inexhaustible abundance”. Various state emblems of South Korea contain Hibiscus syriacus; it is generally considered by South Koreans to be a traditional symbol of the Korean people and culture.

Environmental Protection Value

It can retain dust and has great resistance to harmful gasses.

Garden Use

Rose of Sharon is a deciduous shrub commonly found in gardens. It is prized for its late-season large showy flowers. Its bushy shape makes it suitable for hedging and screens. Rose of Sharon is good for Mediterranean or drought-tolerant gardens. Suggested companion plants include Red Mountain Spinach or Floribunda Rose to make a color contrast.

Medicinal uses

Hibiscus Syriacus have many medicinal benefits. These include:

  • The leaves of Hibiscus Syriacus have diuretic, expectorant, and stomachic properties. 
  • Hibiscus Syriacus is also used to treat itch and other skin diseases, dizziness, and bloody stools with a lot of gas. Mucilage, carotenoids, sesquiterpenes, and anthocyanidins are among the medicinal constituents found in the bark. 
  • The root bark decoction is antiphlogistic, demulcent, emollient, febrifuge, haemostatic, and vermifuge. It treats diarrhea, dysentery, abdominal pain, leucorrhoea, dysmenorrhoea, and dermatophytosis.

Rose of Sharon (Hibiscus syriacus) Details

Common name Hibiscus, Rose of China, Rose of Sharon, Rose-of-Sharon, Shrub Althea
Botanical name Hibiscus syriacus
Plant type Perennial
Hardiness zone 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b
Growth rate Fast
Harvest time Fall
Height 8 ft. 0 in. - 12 ft. 0 in.
Width 8 ft. 0 in. - 12 ft. 0 in.
Sunlight Full sun (6 or more hours of direct sunlight a day)
Flower color Gold/Yellow
Leaf color Green