For a piece of tropical paradise in your own backyard, you can never go wrong with Hibiscus. This showy flowering shrub screams summer. Its many cultivars produce flowers in an unbelievable range of colors, ensuring there is an option for every kind of gardener.
With so much variety in one genus, understanding Hibiscus can be confusing. The wide variety of common names for each species, from Rose of Sharon to Dinnerplate Hibiscus, certainly doesn’t help either. As they all have different climate conditions, care needs and growth habits, understanding which species you’re dealing with is essential to successful growth.
So, what is the difference between Rose of Sharon, Chinese Hibiscus and the Hardy Hibiscus? Which Hibiscus species are hardy? And how can you tell which species will grow best in your garden? We’ll clear up all the confusion and give you the answers you’re looking for.
|Rose of Sharon|
|Easy to Grow|
Let’s start with Rose of Sharon, arguably the most popular Hibiscus species of them all (indicated by its other common name, Common Hibiscus). This plant’s botanical name is Hibiscus syriacus. You may also know it as shrub Althea.
New gardeners often question the difference between this and regular Hibiscus. This question is slightly misleading though, as they are not separate categories. Rose of Sharon falls under the genus Hibiscus, making it a cousin of other popular Hibiscus varieties. Essentially, all Rose of Sharons are Hibiscus, but not all Hibiscus are Rose of Sharons.
The plant traditionally labeled ‘Hibiscus’ as a common name is actually called Chinese Hibiscus, or Rose of China. This species, botanically known as Hibiscus rosa-sinensis, is also called Tropical Hibiscus as it only grows in USDA Zones 10-11 (and occasionally 9 at a stretch).
Hardy Hibiscus, rather than referring to one species, is a category of Hibiscus that can withstand colder weather, growing in USDA Zones 4-9, sometimes 10. The most common of the hardy species is H. moscheutos. Its massive blooms have earned it the common name Dinnerplate Hibiscus, but it is also known as Rose Mallow.
Other less common hardy Hibiscus species include H. grandifloras and H. coccineus. H. syriacus is sometimes included in the hardy category too as it grows in zones 5-8, but the classification is typically reserved for species with larger flowers.
All of these Hibiscus species are part of the Malvaceae family. This makes them relatives of other flowering plants like Hollyhock, as well as essential plants like cotton and cacao.
Althea and Chinese Hibiscus are native to Asia. Althea hails from the southern parts of China, while Chinese Hibiscus is thought to be from China or India, although its true origin is unknown.
Both species’ names were bestowed by Carl Linnaeus, the Swedish botanist responsible for the plant taxonomy system we still use today. They were named after their origins of ‘discovery’ – namely China and Syria. They became wildly popular across European and American gardens, planted both indoors and outdoors, after their introduction in the 17th and 18th centuries.
Both of these species feature as national flowers. Althea was chosen as the national flower of South Korea. It holds great significance in the country, symbolizing eternity and abundance. The flower features in the national anthem and many official emblems, indicating its importance in Korean culture.
Hibiscus rosa-sinensis was chosen as the national flower of Malaysia in 1960 due to its popularity across the country. Here, it is known as Bunga Raya.
Less is known about the history of the H. moscheutos. Its native area is far from its Asian cousins, in parts of Northern America. Many hybrids have spawned since the 1950s, creating a wide range of hardy Hibiscus varieties ideal for the various American garden environments.
The efforts of horticulturalists have produced hardy hibiscus varieties that can withstand temperatures as low as -30F, have purple and yellow flowers (diverging from the traditional red, white or pink), flower continuously and reliably under many conditions, and have different leaf shapes and colors compared to their cousins.
Hibiscus syriacus is tall and impressive, showing off rows of purple, pink and white flowers from top to bottom. These flowers have a stark red center, resembling a bullseye. The bright leaves stand out amongst a sea of deep green, shiny leaves.
Chinese Hibiscus, true to its other common name ‘Tropical Hibiscus’, has a far more tropical appearance. The flowers come in blindingly bright colors reminiscent of island sunsets. Classic red is one of the more common colors, but you may also find bright yellow, orange, pinks, or a mix of them all on one vivid flower. It is typically shorter than syriacus, and is often grown in containers or indoors.
Hibiscus moscheutos is most known for the massive size of its stunning flowers. Rather than small blooms dotted around a larger bush, the flowers of hardy hibiscus have a habit of taking over. They are typically found in red, white or pink, but some cultivars feature purple, yellow, or even blue.
Due to the extensive hybridization, each cultivar looks different, from the color of the blooms to the size, shape and colors of the leaves. However, they can always be identified by their flower size, impossible to mistake for any other species.
In a nutshell, the flowers of Hibiscus rosa-sinensis and Hibiscus syriacus often look similar, but can usually be distinguished by their colors. If the flowers are bright and intense, it’s likely the tropical species. Muted with red centers? Hibiscus syriacus is your answer. If the flowers are closer to the size of your face than the size of your palm, you’ve got a Hardy Hibiscus on your hands.
The main difference between Hibiscus rosa-sinensis and the other two species discussed is in climate. Tropical Hibiscus, understandably, requires a tropical environment to thrive. They are typically grown in USDA Zones 10 and 11, but may tolerate 9 if given some protection.
This is also what makes them ideal indoor or container plants – simply move them indoors when the weather turns and your Hibiscus should continue to thrive.
Both Althea and hardy Hibiscus varieties survive in a far larger range of climates. This provides options for lovers of exotic tropical flowers who happen to live in non-tropical areas.
Rose of Sharons typically grows best in USDA Zones 5-8. In some areas, it may be grown in zone 9, with added caution.
Hibiscus moscheutos and similar species grow well under the largest range of conditions. Many, like Althea, fall under Zones 5-8, but some can survive in Zone 4, while others can thrive in Zones all the way up to 10.
Apart from the regions they grow best in, all Hibiscus species have largely similar care needs, with some differences in watering requirements.
Similar to most flowering plants, Hibiscus needs plenty of sunlight to produce its stunning blooms. As Chinese Hibiscus grows in tropical climates with much hotter weather, they do not need as much sunlight to bloom as the other two.
While Hibiscus rosa-sinensis can bloom with just a few hours of direct sunlight per day, the other two species will require at least six hours of sun per day in cool climates, or a maximum of six hours in warmer climates. These flowers will typically emerge in summer on tropical varieties and through to fall on hardy ones.
Most Hibiscus species need plenty of water to produce plenty of flowers. However, some can live without water for longer than others. Due to higher temperatures, tropical Hibiscus prefers consistently moist, but not waterlogged, soil to keep the plant healthy and the roots cool.
Althea, on the other hand, can handle some dry soil before their next watering. Hardy Hibiscus, found in the wild near rivers and other water sources, thrives on consistently wet soil. Some cultivars may not be as reliant on these conditions as others, but as a general rule, they should remain very well-watered.
Both syriacus and rosa-sinensis are not particularly fussy about soil. They will grow best in rich, loamy soil, but can also grow successfully in poorer soils.
This is especially true of Hibiscus syriacus, which seems to grow vigorously in any kind of soil, no matter the quality. In fact, it is such a prolific grower that is regarded as invasive in some areas, spreading wildly and growing well regardless of poor soil and polluted air.
While fertilizer is not a necessity when planted in good soil, the added nutrients do help the plants flower more often and more reliably. A slow-release fertilizer can be applied once a season, or a liquid fertilizer once a month, for the best results.
Hardy Hibiscus is not so easygoing. As a result of the nutrient-rich environments it is native to, this plant requires high-quality soil to grow well. This means the soil should be enriched with plenty of organic matter and a healthy dose of fertilizer for the best flowers possible.
When choosing a fertilizer for any Hibiscus species, opt for one with moderate amounts of Nitrogen (N), low amounts of Phosphorus (P), and a high level of Potassium (K).
The two main maintenance tasks for all Hibiscus species are pruning and mulching. Mulching helps retain moisture and keep weeds down, keeping your plants fed and happy consistently. Pruning will keep the shrubs tidy and promote flowering. While it is not essential for all plants, Rose of Sharon in particular benefits from regular pruning due to its large size.
Each Hibiscus species features a number of specialized cultivars with their own unique attributes. However, what most gardeners are understandably after, is the look of the flowers.
When it comes to Hibiscus syriacus, you can’t go wrong with any of the ‘Chiffon’ cultivars, coming in delicate pink, soft purple, and pale blue. These cultivars show off sweet inner petals that cover the stamen, masking the typical hibiscus look. For a more classic option, ‘Red Heart’ features stark white leaves with a contrasting red center.
Chinese Hibiscus cultivars are far less muted, coming in the brightest floral colors you can imagine. The traditional red is exemplified by the ‘Painted Lady’ cultivar, with bright edges and a deep maroon center. ‘El Capitolio’ is another red option with a bit of a twist – two flowers in one bloom. And let’s not forget the stunning sunset cultivar ‘Fiesta’, with a color-changing blend of oranges, reds, and pinks.
One of the oldest and most popular Hibiscus moscheutos cultivars is ‘Lord Baltimore’, a red flower with massive petals. ‘Luna White’ and ‘Luna Rose’ display more delicate tones, with ‘Luna Swirl’ sporting a mix of the two colors in a captivating pattern. The recent cultivar ‘Starry Starry Night’ delivers the best of Hibiscus flowers: a red center, swirled with white and pink streaked petals.
In garden design, all Hibiscus varieties are clearly grown for their stunning, showy flowers. But, as shrubs, they also make ideal privacy screens – especially the larger syriacus varieties. Chinese Hibiscus grows well in pots, perfect for outdoor container gardeners or as a houseplant.
However, there is more to these plants than meets the eye. The flowers of these Hibiscus species are edible and come with a range of health benefits. Some studies have shown the potential of this flower to lower blood pressure and cholesterol. In some regions, it is used to treat colds and flu symptoms. You can either dry the flowers and steep them to make a tea or produce Hibiscus extract. Alternatively, use the large blooms to decorate desserts or salads for a delicious botanical feature.
Understanding the nuances between the various Hibiscus varieties can be confusing. Once you understand the similarities and differences between these species, you’ll know what plant you’re dealing with and how best to take care of it, whether you call it Chinese Hibiscus, Rose of Sharon, Dinnerplate Hibiscus, or one of the many other common names each of these groups have.