Hibiscus syriacus 'Diana' - Diana Rose of Sharon Bushes

The U.S. National Arboretum presents Hibiscus syriacus 'Diana', a rose-of-sharon introduction with a flower as lovely as the Greek goddess for which it is named. Lovely, large, pure-white flowers produce little or no seed. Thus, 'Diana' will bloom continuously from late June until frost. This amazing hybrid shrub has excellent, dark green, pollution-resistant foliage. It tolerates extreme heat, drought, and poor soils but will grow best in soils with moderate fertility and moisture.
Recognition: The Pennsylvania Horticultural Society Gold Medal Plant Award, 1991.

Botanical Name: Hibiscus syriacus L. 'Diana'
(NA 32225; PI 347257)
Family: Malvaceae
Hardiness: U.S.D.A. Zones 5 - 8
Development: 'Diana' resulted from the cross of a tetraploid Hibiscus syriacus seedling with white petals and red eye with a heavily ruffled, diploid white seedling made by Dr. Donald Egolf at the U.S. National Arboretum in 1963. The cultivar first flowered in 1964 and was named and released in 1970.
Significance: 'Diana' is distinct because of its waxy, heavy-textured, wide-spreading, ruffled, pure white flowers that remain open for more than one day, heavy dark green leaves, dense branching, and compact, upright growth habit. In addition, since 'Diana' is a triploid, there is little or no seed production, thus enabling the plant to flower freely from late June until autumn, a time when few woody plants are in bloom.
Description: Height and width: 8 feet tall and 7-8 feet wide.
Habit: Deciduous, tall, upright shrub with dense branching to the base.
Foliage: Leathery, semiglossy, dark green leaves more tolerant to ozone pollution and the first autumn frosts than other cultivars.
Flowers: Waxy, heavy-textured, wide-spreading, ruffled, pure white flowers remain open for more than a day. Bloom begins in late June and continues in profusion until frost.
Fruit: A capsule. 'Diana' is a triploid, with little to no seed production.
Culture: 'Diana' is readily cultivated under diverse climatic and soil conditions, but grows best in full sun to partial shade in a sandy loam with a pH of 5.5-7.0. It can endure extreme heat, drought, and poor soils. Flowering will be heavier and growth more compact if planted in full sun.
Propagation: Roots easily from semi-hardwood cuttings under mist, 2000-3000 ppm IBA, in 4-6 weeks.
Landscape Use: Specimen plant, small tree if trained to a single stem, pruned hedge, deciduous screen, background for perennial border, container plant. Adaptable for use in the home garden, parks, industrial complexes and malls.
Availability: Readily available from mail-order firms and retail and wholesale nurseries.

U.S. National Arboretum Plant Introduction
Floral and Nursery Plants Research Unit
U.S. National Arboretum, U.S. Department of Agriculture, Agricultural Research Service, 3501 New York Ave., N.E., Washington, DC 20002