Hardy hibiscus is a member of the Malvaceae (mallow) family. Hibiscus hybrids are vigorous, sturdy, erect, but sometimes shrubby, woody perennials that typically grow to 4 to 8 feet tall and 3 to 6 feet in diameter. Hibiscus hybrid plants are often complex mixtures of different species that are native to the United States, including H. coccineus, H. laevis, H. militaris, H. moscheutos, and H. palustris.
Hardy Hibiscus is winter hardy to USDA Zones 4 or 5, which significantly distinguishes it from the many tropical to semi-tropical hibiscus on the market today. It is easily grown in average, medium to wet soils in full sun. They do best in moist, organically rich soils, but do surprisingly well in average garden soils, as long as those soils are not allowed to dry out. Deep and consistent watering is advisable. They tolerate some light shade, but full sun with good air circulation produces the best flowers, strongest stems, and the best environment for resisting potential diseases. Site them in locations protected from wind to minimize the risk of wind burn. Deadhead individual flowers immediately to maintain plant appearance. Cut back stems to approximately 3 to 4 inches in late autumn. Although they are cut down each fall, the clump will increase in size, providing a larger plant with additional blooms.
Individual flowers grow to 6 inches in length and remain in bloom for only one day, but one or more flowers usually open each day, in succession, over a long mid-summer to early fall (sometimes to first frost) bloom period.
Hibiscus adds an instanttropical feel to any landscape and are perfect specimen plants near a pool or patio. Use them in large containers if you have harsh winters, so they can be brought indoors. Plant in a butterfly or pollinator garden or in groups for a shrub border. They work well in a naturalized or riparian area. This plant is slightly salt tolerant.
Insects, Diseases, or Other Plant Problems: No significant problems, however aphids, Japanese beetles and sawfly larvae can be issues. Leaf scorch can result from allowing the soil to dry out.
Provide full sun in your growing location. Shady spots can result in the stems growing too tall to support the large blooms.
VIDEO Created by Elizabeth Meyer for "Trees, Shrubs and Conifers" a plant identification course offered in partnership with Longwood Gardens.
