Big Flowers Grow on Hardy Garden Hibiscus

There are more than 200 species of Hibiscus grown as perennial plants, shrubs and tropical houseplants. Hardy perennials and shrub plants are able to withstand colder climates while tropical houseplants are kept outside only during warm summer months.

Hardy Hibiscus includes species such as H. coccineus, a native in eastern United States grown in zones 6 – 9 and used around ponds for its tolerance of wetland environments. H. moscheutos is a native plant hardy in zones 4 – 9. Breeders of Hibiscus have used a combination of species to improve plant hardiness making these big flowers more widely available to gardeners.

Cold Tolerant Hibiscus Cultivars

Modern Hibiscus cultivars are hardy enough to tolerant colder weather. But for example, two well-known Hibiscus ‘Lord Baltimore’ and ‘Lady Baltimore’ only tolerate cold as far north as zone 5.

The Fleming brothers, Jim, Bob, and Dave, were well known for their 50 years of hybridizing work with Hibiscus. Their Fleming Flower Fields was located in Lincoln, Nebraska. A collection of their Hibiscus includes:

• H. ‘Kopper King’ is a 4′ tall plant with 12″ diameter white flowers. Red streaks outward to the petal margins from a hot pink eye zone. The leaves are dark purple with a copperish red tinge.
• H. ‘Robert Fleming’ is 3′ tall. The dark red overlapping petals complements the hydrangea-like foliage of this Fleming brothers’ namesake.
• H. ‘Plum Crazy’ is 4′ tall with 10″ diameter purple flowers. The plant has dark purple leaves.

Walters Gardens is another hardy Hibiscus hybridizer but located in Zeeland, Michigan. Their Hibiscus ‘Cranberry Crush’ is 4′ tall, a red heavily textured flower, also hardy to zone 4.

Rose Mallow Flower and Plant Care

Plant care for hardy rose mallow starts with growing it outside in full sun with rich moist well-draining soils. Hibiscus do not favor plant division nor require it.

Hibiscus flowers are similar to petunia flowers; they turn mushy often reminding gardeners of used tissues. Deadheading Hibiscus flowers before that occurs will keep plants blooming longer and looking healthy. Hibiscus plants are favored by bees for their nectar, gardeners deadheading will want to use caution.

Pruning Hibiscus is done primarily in the spring to reduce the plant’s height and will encourage a fuller appearance. Gardeners, who want to avoid early Japanese beetle damage, will cut back plants by ½ in early June.

Hibiscus Shrubs and Tropical Indoor Plants

Hibiscus syriacus is a deciduous shrub, not a perennial. Commonly called rose-of-Sharon, it has similarly shaped flowers.

Hibiscus rosea-sinensis is hardy in zones 10 – 11. It is appropriate for growing as a tropical plant and brought indoors from northern gardens in early fall.

Hibiscus, bred to tolerate colder climates, is a hardy rose mallow plant. Rose mallow has big bold flowers and can be grown in a collection or as a specimen to create drama in a flower garden.

Gardeners who like big plants for flower gardens might like to read about more big flowers or tropical-looking foliage.