Bigleaf Hydrangea

Hydrangea macrophylla

Hydrangeaceae · broadleaf deciduous shrub · introduced

Last updated

Data Maturity Structured

This profile synthesizes data from multiple published sources. Expert field review is in progress.

Bigleaf hydrangea is the hydrangea most people picture when they hear the word, and also the species most likely to disappoint in the Puget Sound lowlands if sited or pruned carelessly. Four field realities drive local performance. First, pruning timing: macrophylla blooms on old wood, and the most common reason a local bigleaf fails to bloom is summer or fall pruning that removed next year's buds. The late-winter window here runs from mid-February through the first week of March, before bud break — and only to remove dead wood and spent flower heads, not to shape. Second, the 2021 heat dome: the late-June 2021 event (108°F in Kent) scorched macrophylla flowers and foliage across the region and killed plants in exposed full-sun sites (Pscheidt, PNW Plant Disease Handbook). Bigleaf hydrangea is now a morning-sun / afternoon-shade plant here by default, not a full-sun shrub. Third, powdery mildew pressure: WSU HortSense maintains a cultivar-resistance list specifically for bigleaf hydrangea powdery mildew, and cultivar choice can eliminate the problem without fungicides. Fourth, flower color: Puget Sound soils are acidic and aluminum-rich by default, so pink-labeled mopheads will typically emerge blue here unless soil chemistry is actively managed. The remontant Endless Summer line (Endless Summer, BloomStruck) is the right pick for late-frost-prone microsites where old-wood bud loss is a recurring problem.

— Chris Welch, ISA Certified Arborist

Bigleaf hydrangea (Hydrangea macrophylla, Hydrangeaceae) is a fast-growing deciduous shrub from Japan (possibly Korea), reaching about 4 feet tall and 9 feet wide with a mounding form. The signature feature is pH-dependent flower color: acidic soil produces blue flowers and alkaline soil produces pink, with white cultivars unaffected. Flowers appear in mophead (spherical) or lacecap (flat-topped) forms from July to August.

Bigleaf hydrangea grows in part shade on adaptable soils (pH 4.5 to 8.0) with moderate water needs, hardy in Zones 5b to 8b. It blooms on old wood; prune after flowering. Disease pressure is notable, with 13 documented associations. Root weevil and foliar nematode are the primary pests. Hundreds of cultivars are in the trade spanning both mophead and lacecap forms. Powdery mildew-susceptible cultivars include 'Nikko Blue,' 'Forever Pink,' and 'Madame Emile Mouilliere.'

Quick Facts

Height
4 ft
Spread
9 ft
Growth Rate
Fast
Light
Part Shade
Soil
Adaptable
Water
Moderate
Hardiness
Zone Zones 5b–8b
Bloom Time
July to August
Origin
Japan

Phenological Calendar

Stage Typical Window
Bud break BBCH 07 Feb 15-Mar 15
Leaf emergence BBCH 11 Mar 1-Apr 1
Fruit/seed development BBCH 71 Jun 1-Aug 31
Fruit/seed maturity BBCH 85 Sep 1-Nov 30
Leaf drop BBCH 93 Oct 15-Nov 30
Dormancy BBCH 97 Nov 15-Feb 28
Leaf emergence BBCH 11 —

Diseases (12)

Pests (2)

Cultivars (6)

''Endless Summer''
The first widely marketed remontant (reblooming) bigleaf hydrangea. Flowers on both old and new wood, so late-frost bud loss does not end the season. Mophead form, flower color follows soil aluminum availability (blue in PNW clay by default). 3-5 ft tall and wide. Discovered at Bailey Nurseries in Minnesota by Hans van der Toorn; introduced in 2003.
The default recommendation for late-frost-prone microsites where old-wood bud loss is a recurring problem. Insurance policy rather than a miracle plant.
''BloomStruck''
Endless Summer line selection with red-purple stems, dark green foliage, and rose-pink to purple mophead flowers. Remontant (reblooming). 3-4 ft tall and wide, more compact than the original Endless Summer.
Choose when a more compact habit is preferred and the dark stem color adds ornamental value.
''Nikko Blue''
Classic blue mophead. Not remontant. Reliable true-blue flower color on acidic high-aluminum soils (the Puget Sound default). 4-6 ft tall and wide. An older cultivar that remains the reference point for blue mophead performance.
Works well on established sites with reliable old-wood bud survival; avoid on late-frost microsites.
''Mariesii''
Heritage lacecap form. Flat flower heads with a central disk of small fertile flowers ringed by large sterile florets. Flower color shifts with soil pH (blue in PNW clay). 4-6 ft.
Pick when the lacecap aesthetic and pollinator value of the fertile center flowers matter more than mass mophead bloom.
''Madame Emile Mouillère''
White mophead heritage cultivar. Flowers open pure white and age with pink or blue tints at the edges depending on soil chemistry. 4-6 ft. Long-standing RHS Award of Garden Merit recipient.
The standard white mophead choice. Works well in shaded beds where white flowers extend visual depth.
''Lady in Red''
Lacecap with red stems, dark foliage, and pink-to-red flower color on alkaline or aluminum-poor soils. On acidic PNW soils typically produces purple-pink flowers. 3-4 ft.
Ornamental stem color adds winter interest. Smaller scale fits mixed borders.