Botanically known as Hibiscus moscheutos [hi-BIS-kus, mos-KEW-tos], hardy hibiscus is a summer herbaceous perennial hibiscus.
These hybrids are a popular species related to the flowering, Tropical Hibiscus tree, which is a genus in the mallow family Malvaceae.
The genus is considerably large, containing species which are indigenous to North America and are popularly cultivated in warm temperate or tropical zones in the world.
The deciduous species is set apart by its large, paper-thin flower petals and maroon-hued foliage.
The plant also comes in a wide array of varieties, boasting different flower colors and features.
Hardy hibiscus is known by a few common names which are as follows:
- Rose of Sharon
- Rose Mallow
- Swamp Mallow Hibiscus
- Swamp Rose Mallow
- Holy Grail
- Dinner plate hibiscus
Hardy Hibiscus Care
Size and Growth
A hardy rose mallow hibiscus usually grows up to 7′ feet tall and 3′ to 4′ feet wide and size varies from species to species.
However, some of the most common cultivars grow up to 4′ feet in height and spread slightly less. The Midnight Marvel Hibiscus is a good example.
However, the bloom size is often up to 10″ inches in size. Each bloom lasts only a day or two and is immediately replaced by new petals.
Hardy hibiscus is suitable for Hardiness USDA zone 4 to 8.
The hardiness largely depends on the specific variety.
Typically, hardy perennials are hardy down to zone 4.
The growth rate is slow to moderate.
It usually takes seven to eight years for the plant to fully mature.
Flowering and Fragrance
Hardy hibiscus is admired for its mellow, fuzzy flowers that appear in different colors – white, red, blue, and pink – depending on its variety.
The plant begins to flower in early/late spring, sporting dark-colored foliage usually in black or maroon color.
This provides a great contrast to the light, lovely hue of hardy hibiscus.
The bright blooms (pink red, pink flowers, white flowers, and red flowers) live only a day or two but they come in succession so the bush never loses its beauty.
These hibiscus plants become more beautiful as they age.
They produce more flowering stems and hibiscus flowers with every season.
While most hibiscus varieties have no scent, some of them have moderate fragrance.
They also produce sweet nectar, attracting butterflies and hummingbirds as a result.
Light and Temperature
Hardy hibiscus needs about six hours of full sun daily to bloom to its greatest potential.
Learn more on How Much Sun A Hibiscus Need?
However, plants may not survive if kept in the sun all day long.
It may require partial shade from excessive sun.
The plant also needs to be watered in an adequate amount to stay nourished.
The best temperature range for hibiscus flowers is from 60° – 90° degrees Fahrenheit (15° – 32° C).
Before the temperature goes down to 32° degrees Fahrenheit (0° C), bring the plant inside.
Bringing plants indoors may turn it dry so misting the leaves daily will be the best solution in this regard.
USDA Hardiness zone 4 – 9.
Water and Feeding
Hibiscus needs a lot of nutrients and an adequate amount of watering to live a wholesome life.
Use water-soluble or slow-release fertilizer to ensure the plants get balanced nutrients.
If using a slow-release fertilizer, apply it four times a year, in early spring, late summer, late winter, and after the blooming period.
Learn tips on Hibiscus Flower Fertilizer
Don’t overwater the plant, especially if it is a small one with fewer leaves.
In warm summers, watering a hibiscus plant daily is a must while in frosty winters, water it only when the soil is dry.
Soil and Transplanting
Hardy hibiscus prefers well-drained, moist soil to bloom fully. A houseplant soil is a good potting soil option.
Plants transplant well and the best time for transplanting is early spring but it is also done in the late fall as well.
The day before transplanting, water the plant well, dig up a fairly large root ball and plant it into an already-prepared pot.
Later, cut the shrub, water the plant well, and mulch.
Grooming and Maintenance
Keep the plant away from windy areas.
The bush dies to the soil level in winter; so prune it to the ground in the fall season.
Don’t worry, pruning won’t damage the root system.
New branches and new flowers will pop back in the following year, making it look like a new plant.
Details on How to Prune Hibiscus
How To Propagate Hardy Hibiscus
The most effective way to propagate is by stem cuttings.
- In spring or early summer, cut a part of softwood about 4″ inches long.
- Add in a rooting hormone in a small dish, wet it a little bit, and dunk it in the powder.
- Make a wide hole in the potting mix to place the stem deep into it.
- Thoroughly tap down the planting surface and water it well.
- Cover the pot with a plastic bag and face it toward a warm spot which provides 60° degrees Fahrenheit (15° C) of direct sunlight.
Swamp Mallow Hibiscus Pests and Diseases
Pests, such as suckers and chewers, mainly feed on hardy hibiscus.
Several viral and fungal diseases infect hibiscus plants; plus, a few psychological disorders also occur due to over-fertilizing, nutrient-deficiency, or over/under-watering.
Hardy Hibiscus Uses
The cranberry crush perennial hibiscus coccineus or red eye fireball shrub are best known for their showy quality which is why they are best favored as landscape shrubs.
They can elevate the beauty of any perennial garden and therefore they are used for ornamental purposes.
They also feature lots of pollens and nectars so they help attract insects like butterflies and hummingbirds.