Culture
Easily grown in organically rich, medium moisture, well-drained soils in full sun to part shade. Thrives in moist soils, and appreciates a summer mulch which helps retain soil moisture. Bloom occurs on old wood. Prune if needed immediately after flowering (little pruning is usually needed). Winter damaged stems may be pruned in early spring. Plants should be given a sheltered location and winter protection (e.g., mulch, burlap wrap) in USDA Zone 5, particularly when not fully established. Plants can lose significant numbers of flower buds or die to the ground in harsh winters (temperatures below -10 degrees F), thus respectively impairing or totally destroying the bloom for the coming year.
Noteworthy Characteristics
Hydrangea quercifolia, commonly called oakleaf hydrangea, is an upright, broad-rounded, suckering, multi-stemmed, deciduous shrub that typically grows 4-6' (less frequently to 8') tall. It is native to bluffs, moist woods, ravines and stream banks from Georgia to Florida to Louisiana. It is noted for producing pyramidal panicles of white flowers in summer on exfoliating branches clad with large, 3-7 lobed, oak-like, dark green leaves.
The genus name Hydrangea comes from hydor meaning "water" and aggeion meaning "vessel", in reference to the cup-like capsular fruit.
Specific epithet is in reference to the leaves that look like those of Quercus (oak).
'Piihq-i' is a compact selection of oakleaf hydrangea that features strong stems, good fall color, and white blooms. The 9" long, terminal panicles are made up of showy, white sterile florets and small, fertile florets. The main bloom period falls in early to mid-summer and the sterile florets fade from white to pink as the season progresses. The dark green foliage turns shades of reddish orange and burgundy in the fall. Mature plants will reach up to 6' tall and spread to fill a 5' area. Commonly sold in nurseries and garden centers under the name JETSTREAM. Plant patent number PP25319 applies to this cultivar.
Problems
No serious insect or disease problems. Some susceptibility to leaf blight and powdery mildew. Aphids and spider mites are occasional visitors.
Uses
Effective as a specimen or accent for foundations or other locations near homes or patios. Group or mass in shrub borders or in open woodland areas. Good informal hedge. Exfoliating mature branches provide interesting color and texture in winter.