Recently introduced cultivated varieties of oakleaf hydrangea (Hydrangea quercifolia) enliven contemporary garden landscapes with new colors, sizes, and uses.
Present-day plant breeders like those at the U.S. National Arboretum (USNA) are demonstrating success in producing compact oakleaf hydrangea cultivars with impressive flowering characteristics.
These modern cultivars provide potential for gardeners and landscape professionals to use appropriately proportioned and good-looking selections in currently fashionable small landscapes.
Modern oakleaf hydrangea cultivars provide year-round landscape interest in containers, woodland gardens, and deciduous shrub borders, mass plantings in large areas and firescaping in fire-prone areas.
Retired University of GA horticulture professor Michael A. Dirr in Manual of Woody Landscape Plants: Their Identification, Ornamental Characteristics, Culture, Propagation, and Uses.
2009 lists 15 wide-ranging cultivars of Hydrangea quercifolia of different origin and 12 that result from work done at the Louisiana Nursery, Opelousas, LA.
Spring and autumn leaf colors and flower characteristics, but not size, were criteria for the majority of these selections. Here are characteristics for four dwarf, compact forms.
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In the spring of 2010, the USNA introduced two new oakleaf hydrangea cultivars to the American gardening and landscaping world. Both ‘Ruby Slippers’ and ‘Munchkin’ are dwarfs compared to the native oakleaf hydrangea which may surpass 6 feet with the same to a wider spread.
‘Ruby Slippers’ is a hybrid between ‘Snow Queen’ and ‘Pee Wee’ and grows to about 3.5 feet tall and 5 feet wide while ‘Munchkin’ grown from open-pollinated seedlings of ‘Stikes Dwarf,’ is slightly smaller at 3 feet tall and 4.5 feet wide.
‘Pee Wee’ and ‘Sikes Dwarf’ are two older dwarf cultivars described as approximately 3 to 4 feet in height and width at maturity. Many gardeners and landscape designers are pleased with these varieties regularly sold at online nursery sites and local garden centers.
However, various university publications such as the University of Connecticut Plant DataBase indicate that “dwarf” is a relative term with these cultivars because reports indicate specimens measuring over 6 feet tall.
Dirr speculates on page 514 in Manual of Woody Landscape Plants: Their Identification, Ornamental Characteristics, Culture, Propagation and Uses, 2009 that possibly “something happened in tissue culture or the plants were mixed.”
Hydrangea inflorescences, called panicles, carry two kinds of flowers: insignificant-appearing fertile kinds that produce seeds, and showy sterile kinds. On most cultivars, panicles are approximately ten inches long and sometimes larger. The sterile florets are white and most turn a subtle pink and then brown as they age.
The sterile flowers of ‘Pee Wee’ hydrangeas are white but more refined than those produced by other cultivars, and are borne on 4- to 5-inch long inflorescences. These sterile flowers almost cover the smaller fertile flowers and mature to a deep rose color. ‘Stikes Dwarf’ also produces white sterile florets on somewhat more rounded and lumpy-looking panicles. They are, however, not as abundant as those of ‘PeeWee,’ nor do they turn as deep a rose color.
‘Ruby Slippers’ carries flowers on 9-inch long panicles that are held above the foliage. Sterile florets emerge as white, quickly turn pale pink, and then mature to rose. ‘Munchkin’ produces abundant 6.5-inch long panicles that are also held above the foliage. Florets open white and gradually turn medium pink.