Rose of Sharon is a pleasingly attractive summer flower. Its showy blooms, in shades of purple, pink, red and white last throughout the summer months, attracting butterflies, birds and pollinators to your garden.
Also known as Althea, this popular ornamental flower originates in India and China. Despite its name this plant is not a rose. Instead rose of Sharon (Hibiscus syriacus) is a member of the mallow or Malvaceae family.
Hibiscus syriacus is a reliable way to add color and structure to your garden. The plants bright flowers will also attract scores of butterflies and pollinators.
Suitable for most USDA zones, Hibiscus syriacus is hardy in zones 5 to 9. In ideal conditions, the plant can reach 9 to 12 ft in height and achieve a spread of about 10 ft. This makes it a great statement plant. It is also a good option for natural fencing, helping you to bring privacy to a space. However, the plant’s growth habit means that without regular pruning it can outgrow its space and overcrowd or smother other plants.
Here is everything you need to know about growing and pruning a rose of Sharon plant.
Different Varieties of Rose of Sharon
The rose of Sharon plant comes in a number of pleasingly attractive varieties. While many garden stores sell rose of Sharon plants, consulting specialist nurseries and online stores enables you to access a wider variety of plants. Take the time to explore the available options and select a plant that both appeals to you and suits your growing conditions.
The attractive Tri-color cultivar produces red, pink or purple double flowers. Pink Giant produces large pink flowers, at least 5 inches in diameter. Adding further interest is the flower’s rich red center.
Lucy is a reliable cultivar that can reach a height of 8 ft and a spread of about 6 ft in ideal conditions. It produces large, red-pink flowers.
The Woodbridge variety is particularly attractive, producing pink flowers with dark centers.
While most cultivars produce flowers which have a different colored throat to the rest of the bloom, some cultivars flower in only a single shade.
Minerva produces large lavender or pale purple flowers with a red center. The plant can achieve a spread of about 7 ft and a height of 8 ft. For a more compact alternative, Blue Bird produces bright blue flowers with a red center. The Blue Bird cultivar rarely exceeds 4 ft in height.
Diana is an unusual cultivar. Unlike other Hibiscus syriacus varieties its flowers are one color, meaning that the throat of the bloom is the same color as the rest of the flower. Diana’s white flowers remain open during the evening and night.
Where to Plant
Rose of Sharon does best in rich, well-draining soil. A slightly acidic soil is ideal. The plants tolerate most conditions but try to avoid extremely dry or wet positions.
Plant in either in a full sun or a partial shade position. Older plants can succumb to fungal issues if planted in shaded positions.
The soil should be rich. A pH between 5.5 and 7.5 is ideal.
If you are unsure of the makeup of your soil, try a soil testing kit. These are easy to use and provide you with valuable information such as the nutrient content of your soil. This information helps you to better care for your plants and create a lush, bountiful garden.
How to Plant or Transplant
The best time to plant or transplant Hibiscus syriacus is when the plants are dormant. This is either in the fall or in early spring, usually March after the last frost has passed. Planting or transplanting in the fall gives the plants time to establish themselves, and their root system, before flowering the following year.
Try to avoid planting when the plant is actively growing. This can stress the plant causing it to drop foliage and struggle.
Before planting weed the site well. Work in organic matter such as compost to further improve the soil. Dig a hole twice as large as the container currently holding the plant. Digging to such a size means that the hole is more than large enough to hold the plant’s root ball.
Hibiscus syriacus does best in full sun positions in well draining soil. Planting in a favorable position encourages healthy growth and flowering.
If you are transplanting a large plant, cut it back before you move it. You can also tie up the lower branches to prevent accidental damage.
To remove the plant from its original site, gently dig around the plant. Dig in a large circle, deeply enough to get under the root system. Use a spade or fork to gently lift the plant and as much of the root system intact as possible. Carefully lift the plant from the soil.
If your rose of Sharon is in a container, squeeze the sides to loosen the soil before sliding the plant out of the container.
Position the plant in the hole. It should sit at roughly the same depth as it did in its previous position. When you are happy with the position of the plant backfill the hole, being careful not to accidentally sink the plant too far into the ground.
Gently firm the soil down and water well.
Planting in Containers
You can also plant rose of Sharon in pots.
Make sure the pot is large enough to hold the fully grown plant. It should be clean and have drainage holes in the bottom. Adding a layer of pebbles or small stones to the bottom of the pot helps to further improve drainage.
Fill the pot with fresh, well draining potting soil and plant as described in the ground. Water well.
How to Care for Rose of Sharon
Once planted, Hibiscus syriacus care is pleasingly straightforward.
When to Water
Once established, rose of Sharon is pleasingly tolerant of dry periods. Yellowing foliage is often a sign of overwatering and not, as is the case with other plants, underwatering.
Water only when the top two to three inches of soil feels dry. Soak the soil, allowing the roots to take on as much moisture as they need. Allow the soil to dry out before watering again.
When watering, try to keep the foliage as dry as possible. Watering in the morning gives the foliage time to dry out. Keeping the foliage dry helps to prevent mildew and other diseases.
Plants in containers may require more regular watering. If you want to create a low maintenance garden, try planting in a self watering container.
Fertilizing Rose of Sharon
Enrich the soil before planting by working in nutrient rich organic matter, such as compost into the soil. This gives the plant a nutritional boost, helping it to settle in its new position.
You should also regularly fertilize your plants with a general purpose feed during the growing season. Apply 1 tablespoon per foot in height. Feed once at the start of the growing season and again in midsummer.
A top dressing of mulch or organic compost helps the soil to retain moisture. As the material breaks down it returns nutrients to the soil, giving plants a natural nutritional boost.
For an organic alternative to chemical fertilizers try applying a top dressing of organic compost at the start of the growing season. Repeat this application again in midsummer, if the top dressing has broken down.
If you are unsure how much fertilizer to apply, remember less is more. Over feeding can cause more harm than good, turning leaves yellow or causing them to die out. Applying a slow release fertilizer, such as Jobe’s Organics Slow Release Plant Food, also helps to reduce the risk of over fertilizing.
While balanced fertilizers are fine, avoid fertilizers rich in nitrogen. These encourage foliage production at the expense of flowering and root development.
How to Overwinter
Hibiscus syriacus is hardy in USDA Zones 5 to 10.
To help your plant survive winter cease feeding in midsummer. This discourages new growth, which is susceptible to frost damage from emerging.
In cooler zones, make sure that you protect the crown of the plant. Applying a thick layer of mulch insulates the crown, protecting it from deep freezes. Potted plants can also be mulched or covered with straw or a horticultural fleece, such as the Valibe Plant Cover.
Rose of Sharon looks particularly effective planted alongside other flowering or evergreen shrubs in a natural border. This provides year round color and interest. Popular evergreens that work well with rose of Sharon include holly and boxwood.
Good companion plants also include flowering shrubs such as:
Rose of Sharon works well with a range of other plants. Just make sure that you properly space out your plants, this helps to prevent smaller plants from becoming overcrowded and smothered.
You can also use Rose of Sharon as a backdrop against colorful flowering plants. Perennials that work well include:
Low growing plants such as hosta, verbena and creeping thyme also work well.
How to Propagate
Taking stem cuttings is a reliable way to propagate rose of Sharon.
Cuttings are best taken in early to mid summer. Take cuttings from healthy, green stems. These are branches that have newly emerged and are yet to develop a woody bark.
With a garden scissors take cuttings that are 4 to 6 inches long. The stem should have several leaves and buds. Remove the leaves from the lower half of the cutting.
Dip the cutting in rooting hormone helps to stimulate root production, but is not absolutely necessary. Plant each cutting in a pot filled with fresh, well draining soil. Plant so that the bottom third to half of the cutting is in the soil. Water well.
Cover the pots with a plastic bag or place in a propagator. If you choose to cover the cuttings with a plastic bag, don’t allow the plastic to contact the cutting. This can cause cuttings to fail. Use bamboo sticks to create a protective cage around the cutting.
Place the cuttings in a position filled with indirect light, or a lightly shaded position.
Check the cuttings every day. Don’t allow the soil to dry out.
After about a week you can remove the plastic. Within a month roots should be starting to form. To test if roots are forming, gently pull the stem. If you feel some resistance it is a sign that roots are present. New leaves also begin to emerge once roots are present. Root production can take up to two months, so be patient.
Allow the cuttings to develop at least two inches of new growth before transplanting.
Propagating from Seed
If rose of Sharon is not considered invasive where you live you can harvest the seeds to plant. Unlike propagation by cuttings, seeds don’t give true replicas of the parent plant.
To encourage seed production, allow spent flowers to remain on the plant. As these fade they give way to seed pods.
Green seed pods tend to emerge in October. These can take 6 to 14 weeks to mature and ripen. As the pods ripen they turn brown. The lobes of the pod then begin to split. Cut the pods away from the plant when they begin to turn brown, before the seeds split.
Alternatively, tie a paper bag over the pods. As the pods ripen and split the bag collects the viable seeds.
Allow the pods to dry out before harvesting the seeds. The seeds can be stored in a paper bag in a refrigerator until you are ready to use them.
You can sow the seeds outdoors in the fall, soon after harvesting or indoors 12 weeks before your last local frost date. Alternatively sow in pots and allow to germinate in a sunny position. Transplant when the seedlings are a healthy size and have at least one set of true leaves.
Following germination seedlings require lots of light and water to grow into healthy plants. Remember to protect seedlings and young plants from birds and other animals.
Be careful when planting rose of Sharon. Some varieties can freely set seed. This means that in some areas the plants are considered an invasive species.
Common Pests and Problems
If planted correctly these are largely problem free plants. The most common issue is infestations of Japanese beetles. These are larger than most garden pests meaning that they are easy to spot and pick off the plant. You can also wash infected leaves with soapy water.
Yellowing foliage can be caused by overwatering or by planting in soil that doesn’t drain sufficiently.
Bud drop is caused by either over fertilizing or under watering plants.
A failure to flower can have a number of different causes. Planting in an overly shaded position can discourage flowering as can allowing the plants to sit in dry soil for an extended period.
Plants failing to flower can also be a sign of rot. This is common after particularly wet periods.
Finally, a lack of phosphorus can lead to plants failing to flower. High phosphorus feeds or bone meal can be applied to help amend the problem.
Deadheading and Pruning Rose of Sharon
Warning Some varieties are fertile and scatter many viable seeds every year. If allowed to these seeds quickly sprout. This means that in some areas the plant is considered as a weed or even as an invasive species.
To control the spread of the plant, deadheading spent blooms before seed pods have the time to develop. You can also grow sterile cultivars such as Diana, Minerva, Lavender Chiffon or Sugar Tip. These varieties don’t set seed meaning that they won’t spread through the garden.
Rose of Sharon flowers form on the new year’s growth. This means that you can prune the plants a number of times during the year. The most common time to prune the plant is in late fall or during the early winter after the leaves have fallen. You can also prune in the spring, before buds have formed.
Young plants benefit from light pruning, older plants may be better if you prune more extremely.
How to Prune
Before you begin to prune, stand back and look at the plant and its shape. Work out what shape you want the plant to achieve and try to prune to that.
Young plants are often more erect and have an upward growth habit. Older plants often have drooping branches. Pruning with the natural shape of the plant makes keeping it under control much easier.
With a sharp shears, begin by pruning away dead or damaged branches. You can also prune away any branches that are growing in the wrong direction.
Remove the old and tall stems first. This helps to keep the plant open and encourages air to circulate freely through the branches.
Thin out any branches that may block sunlight reaching the center of the plant. Try to allow a space of 8 to 12 between the inner branches.
As you prune remove weak branches completely. Cut healthy branches back to the first or second node. Nodes are bumps on the branches from which stems or leaves emerge. If the plant is particularly untidy, it may require pruning further down the stem.
Regularly step back to check the shape of the plant. From a slight distance it is easier to see how your actions are affecting the shape and balance of the plant.
Pinch out any upright growth, particularly upright growth at the top of the plant. This stunts the upward growth habit. Instead more side branches are produced, creating a bushier plant.
Finally, remove any suckers that are emerging from the base of the trunk.
Plants that havent been pruned in a number of years can be cut back to about two thirds of their height. You can cut down closer to the ground if you wish. While this may inhibit flowering for a year or two eventually it helps to renew the plant, meaning that the plant will grow and flower profusely in the coming years.
Regularly pruning your plants helps to keep them healthy. It also encourages larger and more flowers to form.
Bright and reliable, Hibiscus syriacus attracts scores of pollinators to your garden.
Bright, colorful and easy to grow. With a little regular pruning the rose of Sharon is one of the most reliable and colorful additions to your garden.