Jerry Parsons, Extension Professor Emeritus
Texas A&M Agrilife Extension Service
The giant–flowered rose mallow has the largest flowers of any hardy perennial. These are descendants of the native hibiscus found in Louisiana and other Gulf South states. When hybrids of these first appeared many years ago, they were sold as “The Mallow Marvels.” Because of their continuing display of summer color, they still deserve the “Marvel” label. They are among the most spectacular and easily grown plants. Ying Doon Moy, research and development horticulturist at the San Antonio Botanical Center cross–bred a Hibiscus moscheutos hybrid with Hibiscus grandiflorus to create the largest, open–face hibiscus flower in the world. The phenomenon of hybrid vigor (the offspring is superior to either parent) resulted in huge, rose–pink flowers of the new variety named Moy Grande. Hibiscus moscheutos ‘Southern Belle’, which usually has 8 inch diameter blooms, was cross–bred with Hibiscus grandiflorus, which usually has 10 inch blooms, to create Moy Grande which has 12 inch blooms. Most gardeners have been settling for the comparatively small 8–10 inch blooms.
Perennial hibiscus prefer a sunny location and well drained soil containing plenty of organic matter and nutrients. Rich, moist soil and full sun bring the most vigorous growth but mallows are very accommodating and will tolerate light shade and less desirable soils.
Perennial hibiscus flowers removed from the stem are popular for table decorations. They need not be placed in water to prevent wilting which adds flexibility to their use. Each flower lasts a full day before withering. If one wants flowers for the evening, blossoms should be cut as soon as they are fully open in the morning and placed in the refrigerator until just before using. Following the refrigeration period, flowers should remain open for at least four hours.
Hibiscus can be used as container plants as well. Growing hibiscus in containers with a proper potting mix avoids many problems for the gardener. This includes root knot nematode and cotton root rot so frequently encountered with plants grown in soil. Individual flowers last only a day, but each plant may flaunt a number of giant flowers at once. Few garden plants provide so much enjoyment for so little care. Now you can have a plant with the largest flowers in the neighborhood when you plant the new Moy Grande perennial hibiscus.