Common Name: smooth hydrangea
Type: Deciduous shrub
Family: Hydrangeaceae
Zone: 3 to 9
Height: 3.00 to 5.00 feet
Spread: 3.00 to 5.00 feet
Bloom Time: June to August
Bloom Description: White
Sun: Part shade
Water: Medium
Maintenance: Low
Suggested Use: Hedge, Rain Garden
Flower: Showy, Good Cut, Good Dried
Tolerate: Rabbit, Erosion, Clay Soil, Dry Soil, Wet Soil, Shallow-Rocky Soil, Black Walnut
Culture
Easily grown in average, medium moisture, well-drained soils in part shade. Tolerates full sun only if grown with consistent moisture. Can adapt to a variety of soil conditions, but intolerant of drought. The foliage tends to decline considerably in dry conditions. Plants may die to the ground in harsh winters. Bloom occurs on new wood, so plants may be pruned back close to the ground in late winter to revitalize and to encourage vigorous stem growth and best form. If not pruned back, any weakened and/or damaged stems should be removed in early spring.
Noteworthy Characteristics
Hydrangea arborescens, commonly known as smooth hydrangea or wild hydrangea, is a loosely and widely branched deciduous shrub that typically grows to 3-6’ (less frequently to 10’) tall. It is native to moist or rocky wooded slopes, ravines, streambanks and bluff bases from New York to Florida west to Iowa, Missouri, Oklahoma and Louisiana. Gray-brown stems are clad with opposite, broad egg-shaped to rounded, sharply toothed, dark green leaves (2-6” long) with pale green undersides. Leaves turn yellow in fall. Tiny white fertile flowers bloom in May-July in flattened hairy clusters (corymbs to 2-6”across). Scattered continuing flowering may occur throughout summer to September. A few large sterile flowers usually appear at the cluster margins (usually not enough for a quality lacecap effect). Flowers give way to dehiscent seed capsules which ripen in October-November.
The genus name Hydrangea comes from hydor meaning "water" and aggeion meaning "vessel", in reference to the cup-like capsular fruit.
Specific epithet comes from arbor meaning "tree" in reference to the similarity of this shrub to a small tree.
'Grandiflora’ is a smooth hydrangea cultivar that was discovered growing in the wild in Ohio around 1900. It produces much showier flowerheads than the species. Large asymmetrically rounded flowerheads (corymbs to 6-8” across) consisting mostly of large showy white sterile flowers bloom in late May to June for up to two months, sometimes with a small repeat bloom in the fall. Dark green, serrate leaves (3-8” long). A Royal Horticultural Society of Great Britain Award of Garden Merit plant (1993).
Problems
Many species of hydrangea, including this one, are susceptible to bud blight, bacterial wilt, leaf spots, mold, rust and powdery mildew. Watch for aphids, mites, scale and nematodes. Pruning stems back to the ground in late winter each year helps promote stem vigor. Rabbits tend to avoid this plant.
Uses
Mass or group in part shade areas of the mixed shrub border, woodland garden or as background for a perennial border. Naturalize species plants in woodland or native plant gardens. Named cultivars often make showy specimens.