Big-leaved hydrangeas are valued for their showy flowers, however, these small shrubs from Japan are generally not flower bud hardy in cold winters in Zone 5 and colder. This type of hydrangea sets its flower buds on previous year's growth making them more susceptible to freeze damage. In recent years, some cultivated varieties have been developed that are somewhat hardier, but will do better if placed in a protected location and covered with snow throughout the winter.
Blue flowers are one of the plant's appeals, but big-leaved hydrangeas only have blue flowers when planted in acid soils. In alkaline soils, such as those in most of the Chicago region and the Great Plains, the flowers will be pink. Flower clusters will vary by cultivar. Some cultivars have large clusters of mostly showy (sterile) flowers, with a few non-showy (fertile) flowers in the interior of the cluster. These are often referred to as mopheads. Other cultivars have lacecap-type clusters. These usually feature a center of non-showy (fertile) flowers surrounded by an outer ring of the showy (sterile) flowers.
The species and older cultivars bloom on old wood. In zone 5, the plant often dies to the ground and there is no old wood and thus, no flowers. Many newer cultivars will bloom on old or new wood. If the old wood dies, the plant can still bloom on new wood.
This plant has some cultivated varieties. Go to list of cultivars.
- Deciduous (seasonally loses leaves)
- Mixed border,
- Small shrub (3-5 feet),
- Low-growing shrub (under 3 feet)
- Partial sun/shade (4-6 hrs light daily)
- Zone 5 (Chicago),
- Zone 6,
- Zone 7,
- Zone 8,
- Zone 9
- Acid soil,
- Moist, well-drained soil
- Early summer,
- Mid summer,
- Late summer,
- Early fall,
- Mid fall,
- Late fall
Size and Form
Typically 3 to 5 feet high and 3 to 5 feet wide; cultivars can vary in size.
Multi-stemmed, rounded form.
Tree & Plant Care
Best in part shade, some cultivars will tolerate full sun with adequate soil moisture and a layer of mulch.
Plant in a moist, well drained, moderately fertile soil.
Drought sensitive. Water in dry periods.
Protect from winter winds and extreme cold temperatures.
Prune dead stems in early spring, new growth may produce a new flush of flowers in summer.
Newer cultivars bloom on both old and new wood to ensure flowering in zone 5.
Disease, pests and problems
No serious pests.
Native geographic location and habitat
Native to Japan.
Bark color and texture
Stems are green to light gray or light brown.
Leaf or needle arrangement, size, shape, and texture
Simple, opposite leaves with toothed margins; 4 to 8 inches long.
Flower arrangement, shape, and size
These plants bloom mostly on old wood. Severe winters will kill flower buds, but leaf buds survive.
Large flower clusters may vary by cultivar. Some cultivars have large clusters of mostly showy (sterile) flowers, with a few non-showy (fertile) flowers in the interior of the cluster. These are often referred to as mopheads.
Other cultivars have lacecap-type clusters. These usually feature a center of non-showy (fertile) flowers surrounded by an outer ring of the showy (sterile) flowers.
Flowers can be blue in acid soils but will be pink in alkaline soil.
Fruit, cone, nut, and seed descriptions
The actual fruit (a dry capsule) is not ornamentally important, but the remains of the dry flower heads that surround them do provide winter interest.
Cultivars and their differences
All Summer Beauty (Hydrangea macrophylla 'All Summer Beauty'): Mophead-type flower cluster. Nearly rounded flower heads are up to 8 inches across; blue in acid soil, pink in alkaline soil. Flowers on both old and new wood.
Blushing Bride (Hydrangea macrophylla 'Blushing Bride'): Mophead-type flower cluster. White (semi-double) flowers, blush pink with age. Blooms on new and old wood. Part of the Endless Summer® Collection.
Endless Summer® (Hydrangea macrophyll 'Bailmer'): Mophead-type flower cluster. Pink flowers (blue in acid soils). 3 to 4 feet tall. Blooms on new and old wood. Inconsistent bloomer.
Light-O-Day® (Hydrangea macrophylla 'Bailday'): Lacecap-type flower cluster. White showy sterile flowers on the outer ring surrounding small pink fertile flowers. Blooms on new and old wood. Variegated foliage.
Nikko Blue (Hydrangea macrophylla 'Nikko Blue'): Mophead-type flower cluster. Large rounded flower clusters; blue in acid soil, pink in alkaline soil. Blooms on last year's woody stems, leaving flower buds vulnerable to winter damage. Seldom blooms in zone 5. Dark green leaves in summer.
Pia (Hydrangea macrophylla 'Pia'); Mophead-type flower cluster. Dwarf cultivar growing only 2 feet tall. Pink flowers. Blooms on old wood only, but considered hardy to zone 5.
Twist-n-Shout™ (Hydrangea macrophylla 'PIIHM-I'): Laceccap-type flower cluster. Blooms on both old and new wood. Sturdy red stems support abundant flowers in which deep pink is surrounded by pink or periwinkle blue, depending on soil type. Glossy deep green leaves turn burgundy in fall. Part of the Endless Summer® Collection.
Variegata (Hydrangea macrophylla 'Variegata'): Lacecap-type flower cluster. Rosy pink flowers up to 4 inches wide; variegated leaves with light and dark green areas and creamy or silvery-white margins. Flowers on old wood only.