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Differentiating and Caring for the Rose of Sharon Hibiscus

Dorothy is a master gardener, former newspaper reporter, and the author of several books. Michael is a landscape and nature photographer.

There are over 200 different species of hibiscus plants around the world, each variety differing in size, shape, and color. Some of those species are tropical and some of them are hardy. One example of a hardy species is the Rose of Sharon (Hibiscus syriacus).

If you are more than slightly confused over different flowers, you are not alone. Trying to recognize them when they are often so similar in appearance sometimes requires a master gardener or a botanist, and I am neither of those. I depend upon many reference guides when I write articles about gardening and flowers and still remain confused at times. It is my understanding, however, that the Rose of Sharon is simply one specific type of hibiscus. So, to put it quite simply, all Rose of Sharon flowers are hibiscus, but not all hibiscus flowers are Rose of Sharon.

One thing is for certain, however, if you plant several different types of hibiscus in your yard—as you can see from some of the photographs here—you can count on having a fabulous display of colors in your garden.

When, Where, and How to Plant

If you are planting a Rose of Sharon shrub, do so in the spring or fall and select a site that has full sun to light shade. Make sure you have moist, but well-drained soil.

Space your shrubs several feet apart, taking into consideration the expected size of the shrub at maturity. Dig the hole for the shrub only as deep as the root ball, but two to three times as wide.

This is an example of Hibiscus syriacus Blue Bird, which is a Rose of Sharon, but it is also referred to as a blue hibiscus. Yes, it is all very confusing to many people.

This is an example of Hibiscus syriacus Blue Bird, which is a Rose of Sharon, but it is also referred to as a blue hibiscus. Yes, it is all very confusing to many people.

Rose of Sharon: What to Expect

The Hibiscus syriacus (Rose of Sharon) is a deciduous shrub that is vase shaped and upright, often reaching a height of several feet. The shrub bears large trumpet-shaped flowers that have prominent yellow-tipped white stamens.

The individual flowers are available in a variety of colors, although each is short-lived, blooming for only one day. The good news, however, is that a shrub produces a lot of buds on its new growth, which provides prolific flowering over a long blooming period in the summer.

The Rose of Sharon has a medium growth rate, growing about 12–24 inches a year. When your shrub is mature, it can grow up to 12 feet tall and have up to a 10-foot spread. When the Rose of Sharon is young, you can expect to see an upright growth pattern presenting a very compact appearance. As it ages, however, it will begin to spread out, causing many gardeners to consider them an invasive plant.

If you need to transplant your Rose of Sharon, the best time to do so is when it is dormant from late fall into early spring, when it sheds its leaves and has little or no growth.

Fertilizing Your Rose of Sharon

When you initially plant your Rose of Sharon shrub, add a small amount (two to three teaspoons) of a general-purpose fertilizer, which will provide enough nutrients to sustain the plant for its first year. Simply mix the fertilizer in with the soil while you are filling the planting hole. It will disperse as you water and be available for the roots of the plant to absorb.

Fertilization should be done each spring and summer, although the type of feeding is different for the seasons. In the spring, you can apply the same small amount of general-purpose fertilizer that you applied at the time of planting, following the directions provided by the manufacturer.

In the summer, you will need to add some nitrogen to the soil, but I suggest a natural fertilizer such as ramial chipped wood (RCW) mulch, which is made from small, freshly-cut twigs and branches. Branches and twigs that are used are under 3" in diameter and have considerably more nitrogen, phosphorus, potassium, calcium, and magnesium than larger branches.

The wood is put in a chipper or shredder and ground into the mulch, which is rich in nitrogen—but only for the first three months after it is made. The mulch will lose many of the beneficial nutrients after that time. Apply this mulch in the same way you would apply any other mulch (about 2 inches thick), being careful to avoid any close contact with the main stem of your plant. In fact, keep the mulch approximately 18 inches away from the base of the shrub and spread it out to the plant's drip line.

Pests and Diseases

The growth and appearance of your Rose of Sharon can be affected by various pests, such as aphids and Japanese beetles, and diseases like canker and leaf spot, all of which are discussed below.

  • Aphids are the cause of many headaches for gardeners, as they remove fluids from the plant's foliage for nourishment. Your plant will not be able to function without the fluid, and over time the growth of the plant will be stunted and the leaves will begin yellowing. My suggestion to get rid of aphids is always to release ladybugs in your garden to eat the aphids, a method I prefer over insecticides. I believe biological control is always the safest and most preferred way to take care of plants (and your children and pets that have access to your garden).
  • Japanese beetles will work in groups and eat both the leaves and the flowers, leaving the plant nothing to photosynthesize. If you are plagued by these guys on your plant, however, you may have to resort to insecticides, as all life cycles of the pest must be removed, avoiding further damage over time.
  • If your Rose of Sharon plant has smaller leaves than normal and/or damaged stems, you could be facing a disease called canker. You need to remove all of the infected areas in order to stop the spread of this disease that can ultimately kill your plant if left untreated. Afterward, make sure you clean any pruning tools used in the process. If you use those tools again, you could be aiding in spreading the disease.
  • Always water the Rose of Sharon's soil and not the plant's foliage, which will help to prevent leaf spots, which are caused by fungus spores flying through the air. The spores will land and grow in the moist areas of a leaf and form tiny brown spots, which will ultimately become brown, dead areas covering the entire leaf. If you have leaves that already have spots, remove the damaged leaves so the fungus is isolated. If you have a more widespread problem, you may have to resort to fungicides.

© 2018 Mike and Dorothy McKenney


Mike and Dorothy McKenney (author) from United States on April 13, 2020:

We have moved and unfortunately, I don't have any Rose of Sharon trees at this time. Thanks for reading.

Swapna Kollu on April 09, 2020:

I'm interesting in some of the cuttings of rose of sharon trees. Please let me know if you can give me when you prune them.