Hydrangea macrophylla 'Nikko Blue'

Tried and Trouble-free Recommended by 8 Professionals
Common Name: bigleaf hydrangea
Type: Deciduous shrub
Family: Hydrangeaceae
Zone: 6 to 9
Height: 4.00 to 6.00 feet
Spread: 4.00 to 6.00 feet
Bloom Time: July to August
Bloom Description: Blue in acid soil; Pink in alkaline soil.
Sun: Part shade
Water: Medium
Maintenance: Medium
Flower: Showy

Culture

Best grown in rich, medium moisture, well-drained soil in part shade. Tolerates full sun only if grown with constant moisture. Soil pH affects flower color (blue color in highly acidic soils and pink color in slightly acidic to alkaline soils). Add aluminum sulfate to soil to make flowers bluer or add lime to soil to make flowers pinker (add any such soil amendments to plant root zone in late autumn or early spring). Bloom occurs on old wood. Prune any time after flowering by cutting back flowering stems to a pair of healthy buds. Prune out weak or winter-damaged stems in early spring. Only winter hardy to USDA Zone 6. Can be grown in Zone 5 with winter protection (e.g., mulch and burlap wrap), but may lose significant numbers of flower buds or die to the ground in harsh winters, thus respectively impairing or totally destroying the bloom for the following year.

Noteworthy Characteristics

This big leaf hydrangea cultivar is part of the hortensia or mophead group (large sterile florets arranged in globular or "mophead"-like panicles). It is a deciduous shrub with a rounded habit which typically grows 4-6' tall. Features clusters of pink or blue florets in large, rounded, 4-5" panicles (corymbs) which bloom in June (often earlier than other varieties) for up to two months. Large, serrate, obovate to elliptic, lustrous, medium green foliage.

Problems

No serious insect or disease problems. Some susceptibility to bud blight, bacterial wilt, leaf spot and mildew. Aphids are occasional visitors. Lack of winter hardiness is a significant problem in northern climates (see General Culture section above.)

Garden Uses

Group or mass in a sheltered location of the shrub border. Also a good specimen or accent for protected locations near homes or patios.