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Who does not recognize the hardy hibiscus plants seen from South Africa to the United States? Yes, even in Africa, you find this flower growing.
While the hardy hibiscus is a heat-loving show stopper in the garden, there is more to this plant than what the eye sees.
So, today we will help you care for the perennial hibiscus to make sure those large bell-shaped flowers keep blooming.
About Perennial Hibiscus
Before we care for the hardy perennial hibiscus, let us enjoy a history lesson first about this plant. Aah, a history lesson. Yes, and it is an interesting one. The plants are considered ancestors of the native tropical hibiscus growing in Hawaii, Madagascar, Fiji, and Mauritius.
It is an exotic plant, and the species can be traced back to China or is it India. Yet, in the species, you find some hardier cousins that we will look at today, the Hibiscus moscheutos or the perennial hibiscus.
Gardeners also refer to it as the rose mallow or the swamp rose mallow. You find these plants growing in North America. The good news is that when you grow them in the garden, they are easy to care for compared to the tropical hibiscus.
The fascinating thing is that one plant can bloom dozens of flower buds that develop to ten inches long. The flowers last about two days, and when it dies, it forms another bud. Hence, you get long successions of the blooms.
Furthermore, it grows in a shrub-like form blooming from mid-summer to fall. Some hardy hibiscus plants have rounded deep green leaves with serrated edges. Others have maple-type leaves that are deeply cut, while other plants have burgundy foliage.
The perennial hibiscus can grow up to six feet tall with multiple upright stems each spring. While not an evergreen plant, they die back to the ground in winter.
Hardy Hibiscus Plants Care
To grow hardy hibiscus plants, it helps to know the USDA garden zones in your region. The rose mallow does well in zones five to nine, but your tropical hibiscus flowers flourish more in warmer temperatures.
Soil Mix for Hardy Perennial Hibiscus Plant
Okay, choosing the correct soil depends on where you live, and it helps to find a suitable spot. The Hibiscus moscheutos does not like transplanting and does best in rich, well-draining soil. The best time to plant them is in spring or fall.
The species prefers an acidic environment growing in pH levels of 5.5 to 7.5. If you feel the soil pH is low, you can add some peat moss to the potting soil or the bed before you plant it.
Some growing tips for your outdoor plants are to provide your hibiscus with enough room between other plants to prevent overcrowding.
Sunlight Needs for Rose Mallow
Whether growing hibiscus indoors or outdoors chooses a spot with full sun, when growing hibiscus in shadier areas, the stems become tall and flop over. If treated as an indoor plant, it may not be able to produce more blooms than the ones grown outdoors.
Your plant needs at least six hours of full sun a day with afternoon shade. If you find your plant sprawls due to the lack of light.
You can use a grow-thru or peony ring for support to keep them growing upright.
Hardy hibiscuses have a history relating to tropical climates. Hence, they do love water. You may find you need to water more in the growing season. As an outdoor plant, you can provide your swamp mallow with mulch to retain moisture in the warm months.
The important thing is to keep your hardy plant hydrated by checking the soil daily. While the flowers do not last long, there are always more flowers sprouting. When winter arrives, keep the soil moist but not soggy to protect it from the frost.
Temperature & Humidity
The hardy hibiscus foliage remains green year-round if you live in warm climates. Yet, the flowers will take a break, but the leaves are vibrant, taking their place. Still, if you live in cold temperatures, your hardy hibiscus is not cold hardy and will die back to the ground.
You can then cut your plant down to six inches above the ground to boost new growth when it becomes warmer. When you prune in early summer, it also promotes growth for the stalk later.
Fertilizing of Perennial Hibiscus
Compared to other perennials, the hardy hibiscus loves feeds. So, feel free to give your swamp mallow a rich flower fertilizer in phosphorus or potassium. Yet, fertilize hibiscus during early summer when the blooms bud.
During winter, your perennial hibiscus plants do not need a feed. The reason is that it can burn the roots as the plant is dormant.
Propagating Your Hardy Hibiscus Plant
Perennial hibiscus plants can propagate from seed or stem cuttings, and we will discuss both methods here for you.
With this method, you can propagate the hardy hibiscus flowers. We recommend sanding the seeds to help bring moisture into them if you get some seeds. You can do this using fine-grain sandpaper.
Next, soak the seed in water overnight and place the seed in the soil. With the tip of a toothpick, you can make a hole. Then sprinkle some soil over the seed in the hole. Water once planted, should take two weeks for your new plants to appear.
With cuttings, you can ensure that your summer garden is complete with both tropical and hardy hibiscus.
Start by taking a cutting from softwood or new growth. Softwood is mainly found in spring and early summer.
You can take six inches of cutting and remove the bottom leaves. It helps to cut below the leaf node.
Next, dip that cut end into some rooting hormone and place in well-drained soil using a mix of potting soil and perlite.
Another great thing is to place a clear plastic bag over the container to keep in the moisture.
Keep the soil damp but not wet until it roots. It should take about eight weeks.
Perennial Hibiscus Varieties
You can find hibiscus in different varieties and the largest flower in some of them. So group some of these favorites to create a splash of color in the garden.
Lady Baltimore Hibiscus
The plant has pink flowers with a dark-eyed center and makes a statement no matter where you grow it. You can plant hardy hibiscus in late spring to summer. It dies back in winter and tolerates most soils. The plant flourishes in full sun as well.
The dinner plate hibiscus has red flowers you find in early spring and continues into early fall. The hibiscus has larger flowers than most other perennials in a garden. It grows upright with a spreading habit of growing well in moist soils.
With this hardy hibiscus, you see pure white flowers with a burgundy eye in spring and summer. It continues to bloom into fall and is a hardy perennial with upright to spreading habit.
Perennial Hibiscus Pests
While growing hibiscus is relatively easy and is a hardy plant, it can become bothered by pests. The first insect to trouble your hibiscus is Japanese beetles that feed primarily on the dinner-plate-sized flowers.
You can handpick them to place in a soapy water container, or you can spray organic insecticide. Other insects are aphids, whiteflies, and sawfly larvae. The latter is a tiny caterpillar living on the underside of leaves. You can use horticultural oil like neem oil to remove them.
Frequently Asked Questions
You can grow the hibiscus in your garden or a container. The important thing is to provide your perennial with full sun, enough water, and not too much fertilizer.
When winter arrives and your hibiscus plants die back, you can cut it six inches from the ground to boost new growth in spring.
The Hibiscus moscheutos you can divide in late spring or before it sprouts. Still, it would be best to handle the roots with tender loving care as they are brittle.
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