Hydrangea macrophylla 'Nikko Blue'

‘Nikko Blue’ bigleaf hydrangea

Hydrangea macrophylla 'Nikko Blue'

Hydrangeaceae

AUTHOR

botanicalgard

Native Region: Cultivated selection; species native to Japan

Plant Type: Shrub

Mature size:

Light:

Part shade

Water: Moderate

Zone: 5–9

Soil pH: Acidic

Mophead and leaves

A blue mophead framed by the broad, toothed leaves that give bigleaf hydrangea its name. Photo: fzkf0c, CC0, via iNaturalist (observation 317519225)

Whole shrub in flower

A whole ‘Nikko Blue’ bigleaf hydrangea shrub in flower. Photo: Michele Dorsey Walfred, CC BY 2.0, via Wikimedia Commons

Bloom close-up

A blue mophead bloom of bigleaf hydrangea, the classic look of Nikko Blue. Photo: paulmnich, CC0, via iNaturalist (observation 106442172)

Blooms and leaves

Blue mophead blooms among the leaves, in Washington, DC. Photo: andrew2285, CC0, via iNaturalist (observation 219893712)

iNaturalist Taxa Page

MBG Plant Finder

Kew POWO

Few shrubs announce summer quite like ‘Nikko Blue’.

Rounded mopheads of blue to lavender flowers [2a] sit above broad, serrated green leaves, [1a] bringing a generous wash of color to a garden border. This is a named cultivar of bigleaf hydrangea, Hydrangea macrophylla, rather than a separate species. [1, 2]

That famous blue is part plant, part place. Flower color responds to soil conditions, with acidic soils encouraging the strongest blues. [1b, 3a] Expect a deciduous shrub around three to five feet tall and wide, with room for its rounded shape to develop. [1a]

Choose moist, well-drained soil, morning light and shelter from hot afternoon sun. [5a] Mulch helps conserve moisture. [5b] ‘Nikko Blue’ is a traditional old-wood hydrangea: its flower buds develop on existing stems, so cutting the shrub back can remove the coming display. [6a, 3b] Remove dead wood as needed and be sparing with other pruning. [6b] In colder gardens, surviving the winter does not always mean the flower buds have survived too. [6c]

Sources:

[1] Royal Horticultural Society — Hydrangea macrophylla ‘Nikko Blue’: https://www.rhs.org.uk/plants/68352/hydrangea-macrophylla-nikko-blue-h/details
[1a] "A vigorous deciduous shrub to 1.5m high with broadly oval, serrated green leaves."
[1b] "Colours vary depending on the pH of the soil, but acid soils produce a striking bright blue flower"
[2] Spring Meadow Nursery — ‘Nikko Blue’ plant profile: https://springmeadownursery.com/plantfinder/nikko-blue-37250
[2a] "Large blue or deep-lavender mophead flower balls smother 'Nikko Blue' hydrangea, a garden classic for nearly a century."
[3] NC State Extension Gardener Plant Toolbox — Hydrangea: https://plants.ces.ncsu.edu/plants/hydrangea/
[3a] "If they flower blue, your soil is acidic (having less than 5.5 pH) and if they bloom pink, your soil is alkaline (higher than 6.5 pH)."
[3b] "Macrophylla hydrangeas bloom on "old growth" and by pruning them after flowering, it will give them time to set buds for next season's growth."
[4] Royal Botanic Gardens, Kew — Hydrangea macrophylla (species-level taxonomy and native range): https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:791637-1
[5] University of Georgia Extension — Growing Bigleaf Hydrangea: https://fieldreport.caes.uga.edu/publications/C973/growing-bigleaf-hydrangea/
[5a] "Bigleaf hydrangea prefers morning sun, afternoon shade and moist, well-drained soil."
[5b] "Apply 3 to 5 inches of an organic mulch, like pinestraw, pine bark or fall leaves, to the soil surface to conserve moisture and control weeds."
[6] UMass Extension — Why Hydrangea macrophylla don’t flower: https://www.umass.edu/agriculture-food-environment/landscape/fact-sheets/why-hydranagea-macrophylla-dont-flower
[6a] "Older cultivars bloom on “old wood” which means that flower buds develop on the stems during the summer the year before they bloom."
[6b] "Pruning should be done in the spring as new growth resumes and healthy, living branches can be determined from dead branches which can be removed."
[6c] "Winter weather can damage hydrangea buds due to low temperatures, fluctuating temperatures, and late frost or freeze events."
‘Nikko Blue’ is a cultivated selection; the Kew link describes its parent species. No garden occurrence or specimen location has been assigned.

Garden sign & QR code

Garden sign · 5″×4″ SVG

Download 5"x4" Garden Sign as an SVG File for Printing

QR code · for maps & labels

Mophead and leaves

Whole shrub in flower

Bloom close-up

Blooms and leaves

Leave a Review Cancel reply