Culture
Best grown in organically rich, medium moisture, well-drained soils in full sun to part shade. Can be trained as a small single trunk tree, but is best grown as a large, multi-stemmed shrub. May display best shrub form if regularly pruned to a height of 6-10’ tall. This is one of the most winter hardy of the hydrangeas. It thrives in urban conditions. Bloom occurs on current season’s growth, so prune as needed in late winter to early spring.
Larger flower panicles can be obtained by thinning the plants to 5-10 primary shoots. In full bloom, the weight of the flower panicles will typically cause the branches to arch downward.
Noteworthy Characteristics
Hydrangea paniculata, commonly called panicle hydrangea, is a vigorous, upright, rapid-growing, somewhat coarsely textured, deciduous shrub that is native to China and Japan. It typically grows to 8-15’ (less frequently to 25’) tall, and features oval to ovate dark green leaves and upright, sharply-pointed, conical, terminal flower panicles (to 6-8” long) containing both fertile and sterile flowers (mostly non-showy fertile flowers) that bloom from mid-summer into fall.
The genus name Hydrangea comes from hydor meaning "water" and aggeion meaning "vessel", in reference to the cup-like capsular fruit.
The specific epithet paniculata refers to the arrangement of the flowers in panicles.
'Bokrathirteen', commonly sold under the trade name of SWEET SUMMER, is a compact cultivar that typically grows to 4-5' tall. It was selected in 2006 from an ongoing breeding program in Boskoop, the Netherlands involving unnamed seedlings of Hydrangea paniculata. SWEET SUMMER is noted for producing dense, broad-conical panicles (to 5" long) of mostly sterile flowers that emerge white in summer but change to light pink. Flowers at the base of the panicles change from white to pink while new white flowers are still emerging at the indeterminate panicle tips. Strong stiff stems hold the flower panicles upright with no drooping. The much smaller fertile flowers are hidden beneath the showier, sterile ones. Flower panicles may be cut for fresh arrangements or for drying, or may be left on the plant where they will persist well into winter. Ovate, serrate, green leaves (to 4” long) produce generally undistinguished, yellow to purple-tinged fall color. U.S. Plant Patent PP21,778 was issued March 15, 2011.
Problems
Some susceptibility to bud blight, bacterial wilt, leaf spot, rust and mildew. Aphids and mites are occasional visitors.
Uses
Mass or group in a mixed shrub border or open woodland garden. Also effective as a lawn specimen, accent or hedge. Provides late summer bloom when few other shrubs are in flower.