Think of 'Hydrangea' and most often, images of large mounds of green leaves dotted with blue or pink, 8 inch droopy pom-poms come to mind. These were grandmother's Hydrangeas, the hortensia group of Hydrangea macrophylla, the kind whose flowers color depended on soil pH. While these Hydrangeas are perfectly lovely and respectable garden plants when used appropriately, there are many other wonderful Hydrangeas often saddled with the image of these rather idiosyncratic shrubs simply because they share the same name. One such exceptional Hydrangea that is very different from its hortensia cousins is Hydrangea quercifolia, the Oakleaf Hydrangea.
Oakleaf Hydrangea is a brash, bold-textured shrub whose leaves resemble those of the Red Oaks, both in size and shape. These amazing look-alike leaves cover the large, 5-8 foot tall and spreading, multi-stemmed shrub with a striking, forest green mosaic, as if the boughs of an oak had been laced into an elaborate, rounded sculpture. The leaves emerge a downy grey color in the spring and are folded upright in pairs like clasped hands. In addition to the marvelous foliar characters, in early summer, Oakleaf Hydrangea sends up foot tall cones of creamy white flowers, like snow-covered mountain peaks appearing from an emerald tree line below. The flowers mature from white to rosy pink. The oak-like foliage stays green until late in the fall when leaves turn brilliant shades of purple, orange and scarlet. Oakleaf Hydrangea's warm brown bark peels and is very handsome both during leaf-fall and throughout the winter - all of this from one ambitious shrub!
This wonderful plant is native to the deep south where it can be seen growing in moist sites and it is very well adapted to many southeastern landscape conditions. It is fully hardy throughout the southeast but may suffer some injury during severe winters in the mountains if temperatures drop toward -10F. The flower buds will be killed when temperatures drop into this range but the plant will live and make an excellent foliage plant under those conditions. Oakleaf Hydrangea prefers moist, fertile, well-drained soil but will tolerate more poorly drained conditions. Full sun or partial shade are best, especially if the roots can be kept cool. It does not do well in very dry areas. There are no serious pest or disease problems with Oakleaf Hydrangea. While this plant is readily propagated from fresh seed it is more difficult to propagate vegetatively. Cuttings taken in early summer can be rooted under mist but special care must be taken to use an exceptionally well-drained rooting medium.
There are quite a number of cultivars of Oakleaf Hydrangea. All of the named cultivars are superior to the straight species in both profusion of flowering and development of fall color (a very variable trait amongst seedling populations). Some of the better known cultivars include: 'PeeWee' which is an exceptionally compact form, only reaching 3 to 4 feet in height with an equal spread; 'Snowflake', with near double flowering; 'Snow Queen', from Princeton Nursery, with exceptional fall color, very large florets and especially upright flower clusters that droop minimally under their own weight; and two selections that Michael Dirr has made for fall color and upright flowering, 'Alice' and 'Allison'.
Oakleaf Hydrangea is a striking shrub for four season interest in the garden. Its bold texture requires care in placement in the garden to find a niche where its brash nature will not overpower the quieter beauty of other garden plants. But Oakleaf Hydrangea makes an excellent statement in a mixed border where it can really hold its own, in a massed planting for real drama, or as a focal plant in smaller gardens. At The NCSU Arboretum (now the JC Raulston Arboretum), Oakleaf Hydrangea is a masterful star in the Shade House, the Mixed Shrub Border and the Model Gardens. Come out to the Arboretum to see Oakleaf Hydrangea take its well-deserved bows in all four seasons of the garden theatre.