Taxonomy and Botany of Hardy Hibiscus Plants
Plant taxonomy classifies the hardy hibiscus plants with which I deal in this article as Hibiscus moscheutos. They also go by such common names as "rose mallows" and "swamp mallows." But I prefer the more descriptive nicknames "hardy hibiscus" and "dinner-plate hibiscus," for these names tell you that H. moscheutos is quite cold hardy despite bearing large blooms that remind one of the tropics.
The information below pertains to cultivars such as 'Disco Belle Rosy Red' and 'Galaxy.' The colors of the most common cultivars are white, bi-colored, or various shades of red or pink, but other colors are now available.
Characteristics of This Perennial Flower
The most popular hardy hibiscus cultivars reach about 2 1/2 feet in height, with a spread slightly less than that, but the measurement more folks concentrate on is the bloom size -- up to 10 inches for 'Galaxy,' for example. As you can see from the picture above, even cultivars with smaller blooms still produce impressive, saucer-size flowers. While each bloom lives only a day or two, they are quickly replaced by newcomers.
Geographical Origin, Planting Zones, Sun and Soil Requirements
The species plant is indigenous to eastern North America.
H. moscheutos cultivars can be grown in planting zones 4-9.
Grow hardy hibiscus plants in full sun and in an average-to-wet soil.
Care for Hardy Hibiscus Plants, Wildlife Attracted to Them
If you are not planting hardy hibiscus plants in a wet spot, then make sure they are adequately watered. Because the blossoms are so large -- yet so ephemeral -- deadheading is recommended after blooming, for aesthetic purposes.
If the spent flowers are allowed to remain, they can look quite messy, detracting from the display value of your specimen.
Since this perennial does die back to ground level in winter, feel free to prune it down to the ground in fall. As alive as the branches may seem in fall, trust me, they will die in winter. It is what lies under the earth (that is, the root system) that will live on. New branches will spring out of the ground the following year from this root system.
But these specimens are slow to push new shoots out of the ground in spring, a fact that is capable of causing great fear on the part of new gardeners. One's initial reaction, upon witnessing their tardiness for the first time, is, "Oh no, the cold temperatures of the winter must have killed off my plant." But exercise a little patience before you write off this perennial and begin planning to replace it with something else. By May in my zone-5 garden, the new shoots finally make an appearance.
Hibiscus moscheutos flowers are plants that attract butterflies.
Uses in the Landscape
Hardy hibiscus plants essentially function as late summer flowering shrubs (even though they are classified botanically as perennials). They will typically bloom in late July or early August in northern climates. This feature makes them valuable specimen plants in landscaping plans that strive for spring-to-fall color, since fewer flowering shrubs bloom at this time than at other times during the growing season.
The species plant is a wetland plant, and hardy hibiscus flowers can be treated as plants for wet soils -- that is, areas where most other plants would not grow well. This makes them useful around water features.
Related Plants, Outstanding Quality
When you think of hibiscus flowers, you probably think first of tropical plants (H. rosa-sinensis), right? If you live in a northern climate, what comes to mind next may be rose of sharon (H. syriacus), but that shrub does not bear large enough flowers to boast a tropical look. If you want a taste of the tropics in the North, grow hardy hibiscus plants (cultivars of H. moscheutos). Some produce flowers the size of a dinner plate (they are sometimes referred to as the "dinner-plate hibiscus" for this reason), which is surely the outstanding quality of these splendid perennials.