Rose Mallow: How to Help Your Swamp Hibiscus Flourish

Updated May 16, 2022
Woman cutting hibiscus flower

Rose mallow (Hibiscus moscheutos) is a large, fast-growing, cold-hardy relative of hibiscus native to swamps and wetlands in the southeastern United States. Its enormous flowers and showy foliage are an asset to perennial borders in many parts of the country.

Rose mallow flower profile card

Rose Mallow: A Stunning Ornamental

This species of mallow, also known as swamp hibiscus, has become increasingly popular in recent years as a native alternative to the tropical hibiscus. Though it is found in wet soils in nature, it grows quite well in ordinary garden soil as long as it has regular irrigation.

Rose mallow bush
  • Flowers - The flowers of rose mallow closely resemble that of tropical hibiscus, growing up to 12 inches in diameter on some cultivars. They are most often seen in either a crimson red or creamy white color, though there are many other colors available.
  • Foliage - The leaves are even bigger, up to eight inches long, and have a deep green color and interesting serrated pattern that make them just as showy as the flowers.
  • Stalks - Rose mallow plants grow as a single branched stalk that emerges from the ground in spring.

The plants grow several inches a day until their flowers open in late summer, reaching a height of six to eight feet (though there are dwarf varieties available as well).

Gardening With Rose Mallow

Rose mallow grows in USDA Zones 4-9 and prefers full sun and rich, moist soil. Long, hot summers are needed to get the plants to the flowering stage, making rose mallow unsuitable for high elevation areas, the Pacific Northwest, and the cool coastal areas of California. It is one of the top perennials for the Deep South, however, where it thrives in the high humidity.

Availability

Rose mallow plants can be found most easily in the South, and to a lesser extent, throughout the eastern half of the country where they are best adapted. They can be purchased online if you don't find them in local nurseries.

Landscaping With Rose Mallow

Rose mallow is very tall and narrow, making it a good choice for narrow beds against a fence or wall. It is also used in the back of a perennial border where it can rise up and put on its show in late summer when most other perennial flowers are fading.

Mother and daughter in garden are looking at hibiscus flower

Since it grows well in constantly saturated soil, rose mallow is a good option for landscaping wet parts of the yard. Incorporate it in bog gardens, water features, and native wetland plantings.

The smaller varieties are suitable for growing in containers, but keep in mind that the plants are dormant in the winter months.

Rose Mallow Care

Rose mallow is fairly easy to grow, but there are a few regular maintenance tasks you should do to help your plants flourish:

  • Rose mallow needs weekly irrigation throughout the growing season.
  • The hybrid cultivars with dinner-plate-sized flowers should be fertilized every few weeks throughout the growing season to support their voluminous growth, though the basic wild species does not require this type of pampering.
  • Staking is often necessary to keep the top-heavy plants from flopping over when they are in bloom.
  • The aboveground portions of the plant will turn brown after the first frost and can be cut to the ground.

Otherwise, this is an easy-care perennial that does not require any type of special maintenance.

Pests and Disease

Rose mallow is generally disease-resistant, but is susceptible to aphids, scale, whiteflies, and mites. Control these with applications of insecticidal soap, neem oil, or a chemical insecticide as needed.

Popular Rose Mallow Cultivars

Plant height, flower size, and color are the main variables when choosing a rose mallow cultivar. All are hardy in USDA Zones 4 to 9.

Hibiscus blue river in bloom
  • 'Anne Arundel' grows to five feet tall with nine-inch, ruffly pink flowers.
  • 'Cranberry Crush' has eight-inch scarlet flowers on four-foot plants.
  • 'Ruby Dot' is a dwarf variety growing about two feet tall, bearing white blossoms with a red center up to 8 inches in diameter.
  • 'Blue River' grows five feet tall with pure white flowers up to 10 inches in diameter and foliage with a slight blue cast.
  • 'Jazzberry Jam' has nine-inch magenta flowers and grows up to eight feet tall.

Big and Bold

These types of hardy hibiscus make an exotic display in places as far north as Maine and Michigan. They are an important source of nectar for native butterflies and will grow in a variety of garden settings, whether a high-profile flower border or a half-wild swamp garden.

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Rose Mallow: How to Help Your Swamp Hibiscus Flourish