Rose of Sharon, Tropical Hibiscus, and Hardy Hibiscus
For a lush tropical look in your garden, the hibiscus family of plants offers a large variety of forms and habits. While there are many types of hibiscus, this article centers on three of the most popular plants.
Understanding which hibiscus is which can be confusing. If you've seen some of these gorgeous flowering plants and wish to have one of your own, it helps to understand the difference so that you may choose the one you like that is best suiting to your lifestyle.
How many times have you driven by someone's front yard and seen an attractive hibiscus, but don't know anything about hem? Which hibiscus are you looking at?
- Rose of Sharon is the tall, woody shrub that seems to grow at the edges of things with lavender or white flowers with a bright red center.
- Hardy hibiscus is the one where you want to stomp on the brakes, pull over, knock at a stranger's door and inquire about the bush with flowers the size of dinner plates.
- Tropical hibiscus is usually seen growing in a container. The low bush offers single or double blooms in colors you never see in the other two. If it's yellow or orange, or a wild combination of exotic hues, that's a tropical hibiscus.
Good To Know:
In general, hibiscus can be recognized by a unique reproductive system which you can see in the photo above. In many common flowers, the male stamens emerge from the center of the bloom along with female pistils. Hibiscus flowers boldly thrust a large central pistil with small stamens growing off the pistil. This arrangement adds to the dramatic flair of this lovely plant.
Rose of Sharon: US Zone 5 - 8
Hibiscus syria, Shrub Althea, or Rose of Sharon is a tall, woody shrub that can be pruned into a tree form. Prune Rose of Sharon into a tree shape by removing low growing side branches in the first or second year in late winter.
Without pruning, it is a beautiful, graceful plant that grows in an upright vase shape up to 12' tall. Leave are dark green, lobed with jagged edges. three to six-inch flowers appear in late summer in lavender, pink, or white with a red center. They attract hummingbirds and butterflies.
This flower is drought tolerant and seems to thrive in hot weather. Plant in full sun to partial shade.
While Rose of Sharon can be invasive, there are several non-invasive cultivars including Aphrodite, Diana, Helene, and Minerva. To avoid troublesome spread in other varieties, deadhead spent flowers.
Rose of Sharon often takes its good old time to leaf out in Spring, so be patient.
Tropical Hibiscus: US Zone 9 - 11
Tropical hibiscus is a low growing shrub that must be brought indoors during cold weather and best grown in a container to avoid root damage during a seasonal move. The flower has often been shown in postcards worn in women's hair. Hibiscus brackenridgei is the State Flower of Hawaii.
Flowers of tropical hibiscus come in a wider variety of colors than the other forms. Three to six inch single or double blooms come in red, pink, yellow, salmon, green, and gaudy multi-colored hues. The plant will produce more blossoms if kept in full sun with some afternoon shade. This heavy feeder prefers fertilizers that are high in potassium (potassium content is indicated by the 3rd number shown on the container of fertilizer).
Most tropical hibiscus plants will last about ten years with the proper care and good luck. Keep soil moist but not soggy.
Overwintering Your Flower
The best way to over-winter tropical hibiscus is to store the plant in its container in the basement. Bring in before the nights cool below 55 degrees F. Leaves may turn yellow and drop by mid to late winter. Water sparingly and do not fertilize during the resting stage. Though tropical hibiscus become rather pathetic looking in late winter, they fare better in the basement than in a sunny room.
A friend and I were once advised to store our hibiscus dry-root by removing the plant from the soil and keeping it in an open plastic bag in the basement during the winter. All our tropical hibiscus died.
Some tropical hibiscus do not over-winter well. Older and more common varieties will last longer, over-winter more successfully, and bloom more profusely than more exotic types.
Tropical hibiscus can be left outdoors during the winter.
Once Spring comes, cut back the shrub for a bushier, fuller plant. Add a light, fresh soil on top.
Bring the container outdoors once evening temperatures remain above 55 degrees F. Fertilize.
Hardy Hibiscus: US Zone 4
Hardy hibiscus, Hibiscus muscheutos, or Dinner Plate Hibiscus is a dynamic late summer bloomer producing vividly colored, 8 - 12" blooms. Despite its tropical appearance, hardy hibiscus can withstand cold winters and is hardy to US Zone 4.
Also called Rose Mallow and Sawmp Mallow, Hardy hibiscus is a late starter, putting out leaves in late Spring, long after all the other plants are green. Though it dies back in winter, cut back stems to 6" above the ground.
Plant in spring in moist, well-drained soil that is rich in organic material. Hardy hibiscus will tolerate wet soil and is deer resistant. Flowers attract butterflies and hummingbirds.
Check the plant tag to make sure you find the cultivar with the largest flowers and large, heart-shaped leaves. Late summer blooms appear in deep red, white, and intense pink. Though blooms only last one day, the flowers keep coming for a month-long show.
Growing From Seed
Hardy hibiscus can be grown from seed, though some plants produce sterile seeds.
Remove seeds from parent plants once the seed pods turn brown in Fall. The seeds will need some cold storage for 2 - 3 months (you can put them in the refrigerator). In early Spring, nick the seed and wrap in a wet paper towel. Place the wet paper towel in a plastic bag but do not seal closed. After 3 days, plant in loose soil and keep moist in a warm, low light area. Move to a bright, sunny window after germination.
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
Questions & Answers
Is the hardy hibiscus resistant to juglone from the black walnut tree?
Juglone refers to a toxic substance exuded by Black walnut trees. It can cause susceptible plants to produce yellow or brown leaves. Foliage may become twisted or wilted and eventually die. Toxic effects can spread up to 80 feet from the trunk and usually below the drip line.
While Rose-of-Sharon or hibiscus syriacus is juglone tolerant, I am not sure about Hardy hibiscus. One might assume that all hibiscus are tolerant. But when in doubt proceed with caution. Maybe you can plant your Hardy hibiscus well away from the Black walnut.Helpful 2
Can I root hibiscus from a cutting?
Hardy hibiscus are easier to root from a cutting than tropicals, although my sister has done well with tropical hibiscus .
Cut a piece of new growth about 4 inches long just below a leaf node. Remove all but 3 outer leaves.
Dip the base of the stem in rooting hormone.
Plant in a mix of potting soil and perlite. Shove your finger into the soil and place the cutting, then backfill the hole.
Make a little "greenhouse" by tenting plastic over the pot using sticks to support the plastic. Do not allow the plastic to touch the leaves.
Keep the cutting in dappled shade.
Keep soil moist.
It may take the cutting up to 2 months to establish. When you see new growth you know the plant is growing. Remove tent.
Some people claim they can root hibiscus in water. Add a few drops of hydrogen peroxide to deter harmful organisms. Change water once a week. First expect to see little nubs form near the base of the stem. Later white roots emerge then tan colored roots. This may take several months. Once the tan roots are growing, plant in loose, moist soil. Keep tender new plant in light shade.Helpful 5
How do you store Hardy hibiscus roots that we're grown in a large pot?
A hardy hibiscus thrives in US plant zones 5 - 8. The plant zones depend on the coldest winter temperatures in a given area. This means that most species of hardy hibiscus can withstand winter temperatures as low as 10 to 20 degrees below zero Fahrenheit. Take a look at a zone map online; there are plenty available. Then find the area in which you live and see what zone your home is in.
If you live in zone 5 - 8, you can simply plant the hibiscus in the ground.
If, however, your hibiscus is the tropical variety, it will not withstand cold temperatures. Many container-grown hibiscuses are tropical and can only be overwintered in zones 9 - 11. These are areas with warm winters.
Double check your plant to make sure that it is the hardy variety so ensure its survival through winter.Helpful 4