Smooth Hydrangea
Hydrangea arborescens · Deciduous shrub, broadleaf, native hardwood
Plant Family
Hydrangeaceae
Tree Category
Ornamental Flowering Shrub
Variety / Cultivar
Wild type (or 'Annabelle' for common cultivated forms with large mophead flowers)
Hardiness Zones
USDA Hardiness Zones 3 through 9, demonstrating excellent cold hardiness and broad climate adaptability across North America.
About This Tree
A multi-stemmed deciduous shrub featuring an upright, rounded, and somewhat loose form. It typically grows via root suckers to form colonies. Known for its prominent, flat-topped or rounded flower heads composed of numerous tiny fertile flowers surrounded by sterile florets.
Leaf Characteristics
Simple, opposite leaves, ovate to elliptic in shape, 4 to 8 inches long, with finely serrated margins and pointed tips. They are bright to medium green in summer and generally lack notable fall color before dropping.
Bark Characteristics
Thin, smooth bark on younger stems that often exfoliates or peels in thin strips as the stems age, revealing lighter inner bark layers on older woody branches.
Growing Information
Origin Region
Eastern North America, ranging from New York south to Florida, and west to Iowa and Oklahoma
Growing Season
Spring through autumn; leafs out in early spring, produces large white flower clusters in summer (June to August), and drops leaves in late autumn entering winter dormancy
Sunlight & Water Needs
Prefers partial shade, especially protection from hot afternoon sun, though it can tolerate full sun if provided with consistently moist, well-draining soil. Requires moderate to high water.
Mature Size
Typically reaches 3 to 5 feet in height with a similar or slightly wider spread. Fast growth rate with a lifespan of several decades.
Special Characteristics
Valued for reliable summer blooming even after severe pruning (since it blooms on new wood), good tolerance for clay soils, and adaptability to shady woodland garden settings.
Wildlife & Ecology
Provides modest ecological support; flowers attract native pollinators such as bees and butterflies, while dense branching offers cover and nesting sites for small songbirds.