If you want a taste of the tropics in the North, grow hardy hibiscus plants. They often produce flowers of a size rare for plants that can survive cold winters. Learn all about how to grow these floral show-stoppers in your own garden.
- Botanical Name: Hibiscus moscheutos
- Common Name: Hibiscus, rose mallows, swamp mallows
- Plant Type: Herbaceous perennials
- Mature Size 2 1/2 feet
- Sun Exposure: Full Sun
- Soil Type: Loamy
- Soil pH: Neutral to slightly acidic
- Bloom Time Spring
- Flower Color: White, red, pink
- Hardiness Zones: USDA 4-9
- Native Area: Eastern North America
How to Grow Hardy Hibiscus Plants
Plant taxonomy classifies the hardy hibiscus plants as Hibiscus moscheutos. They also go by such common names as "rose mallows" and "swamp mallows." Hardy hibiscus are a cold hardy plant despite bearing large blooms that remind one of the tropics. The colors of the most common cultivars are white, bicolored, or various shades of red or pink, but other colors are now available.
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, which is up to 10 inches for Galaxy, for example.
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.
Grow hardy hibiscus plants in full sun.
The species plant is a wetland plant, and hardy hibiscus flowers can be treated as plants for wet soils. So if your landscaping problem is a soggy area where most plants do not grow well, H. moscheutos might be your answer. This makes them useful around water features.
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 and shrivel up so quickly, deadheading is recommended after blooming, for aesthetic purposes. If the spent flowers are allowed to remain, they can look quite messy (especially after a soaking rain), 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, they will die in winter. It 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. Exercise a little patience before you write off this perennial and begin planning to replace it with something else. By May in a zone-5 garden, for example, the new shoots finally make an appearance.
H. 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.
Related Plants Grow
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. For big, show-stopping flowers, you will want to grow a cultivar of H. moscheutos, such as one of the following:
- Lady Baltimore: 5 feet tall, 3 feet wide; flowers light-pink with a deep-pink center
- Robert Fleming: 3 feet tall, 4 feet wide; red flowers
- Summerific Perfect Storm: 3 feet tall, 5 feet wide; flowers light-pink with a deep-pink center