July's Flower of the Month

Oakleaf Hydrangea

(Hydrangea quercifolia)

Increasingly gardeners are looking for native plants for their landscapes. They know that native plants are adapted to our climate and have learned to cope with our pests and diseases. One that I often recommend is the oakleaf hydrangea.

Oakleaf hydrangea steals the spotlight beginning in early May with its elongated clusters of white flowers. As the flowers age, they take on a pinkish cast, and by winter they have turned brown. Individual flower spikes are borne in four- to twelve-inch long, erect clusters that taper to a point. Handsome, five-lobed leaves reminiscent of the red oak decorate the landscape in fall with their bronze or crimson colors. Coarse-textured leaves and peeling bark make it interesting all year.

The blooms condition well and are beautiful in floral designs. One of the most exquisite mass designs that I ever saw featured blooms of oakleaf hydrangea arranged in a silver urn. It occupied the entrance to a district meeting of the Florida Federation of Garden Clubs. I was captivated by its loveliness.

Culture

Optimal growing requirements are moist, fertile, well-drained soil and partial shade. A site with a cool, moist root environment is ideal. The species seems quite disease and insect resistant. If pruning is necessary, it should be done immediately after flowering since flower buds are formed on the preceding year’s growth. Plant oakleaf hydrangea away from the house where its six- to eight-foot-tall form has plenty of space.

Propagation

 Propagation of this native is relatively easy. Seed can be sown and will germinate. Dried flower clusters can be collected anytime from November through January. Inside each flower cluster are hundreds of tiny, brown seeds about half the size of a grain of sand. These seeds can be sprinkled over a seed-starting mix. They should not be covered since light is necessary for germination. Seeds should sprout in about 18 days if the flat is kept in a warm, sunny spot and not allowed to dry out.

 When seedlings are about one inch tall, they should be transplanted to individual four-inch pots. Fertilize with a weak solution of fertilizer, and pinch out the top to encourage branching. When roots fill the pot they can be planted outside. Started in fall or winter, new seedlings should be ready to set out the following fall. Layers and divisions of the parent plant provide new starts, and firmwood cuttings can be taken during the summer.

Kinds

Several cultivars of oakleaf hydrangea are available, including the well-regarded ‘Alice’, ‘Harmony’, ‘Snowflake’, and ‘Snow Queen’. If a large shrub will not fit your landscape, consider dwarf cultivars such as ‘Pee Wee’ or the very new gold-leafed, pink-flowered ‘Little Honey’. Louisiana Nursery in Opelousas has introduced several cultivars that can be ordered from their catalog. Potted specimens can be found at many local nurseries.

 In addition to oakleaf hydrangea, other species exist. The popular mopheads and lacecaps (Hydrangea macrophylla) are the most familiar. As many as 75 additional species exist, including H. serrata, H. involucrata, and H. seemanii. With all these species and others, as well as cultivars of each one, the horticulture trade is experiencing what one nurseryman calls “hydrangea mania.”

 At a Glance

Common name: Oakleaf hydrangea

Scientific name: Hydrangea quercifolia

Pronunciation: hy-DRAIN-juh kwer-se-FOH-lee-uh

Family: Hydrangeaceae

Some relatives: Deutzia, Philadelphus

Hardiness: USDA Zones 5B-9

Salt tolerance: Slight

Size: 6-8/6-8 feet tall and wide

Origin: Native to Southeastern United States

Propagation: Cuttings, seeds, layers and divisions of parent