bloooooooom Eight o's. Don't count, bookmark. Plan a bed

Bigleaf hydrangea 'Nikko Blue'

Hydrangea macrophylla 'Nikko Blue' · Hydrangeaceae Popular

Bigleaf hydrangea 'Nikko Blue' (Hydrangea macrophylla 'Nikko Blue') in flower
Photo: Michele Dorsey Walfred, via Wikimedia Commons (CC BY 2.0)

Large, rounded mopheads of clear, deep blue in acid soil, in early summer. The classic blue hydrangea of seaside gardens.

Size
5 ft tall, 5 ft wide
Zones
6 to 9
Light
Part sun to part shade
Flowers
Late June to early August
Pets
Toxic (mild)
Job in a bed
Anchor

A bed built around bigleaf hydrangea 'Nikko Blue'

The planner designed this bed around bigleaf hydrangea 'Nikko Blue' when this page was made: a 16 × 8 ft (4.9 × 2.4 m) English border in zone 6, part sun. It chose the other plants from the 708 that suit those conditions, and says below why bigleaf hydrangea 'Nikko Blue' stands where it does.

A 16 × 8 ft (4.9 × 2.4 m) bed at eye level in mid July: Bigleaf hydrangea 'Nikko Blue', Green-and-gold, Coral bells 'Firefly', Garden phlox 'Jeana', Siberian iris 'Caesar's Brother', Columbine meadow rue, Easter lily, Camassia.
A 16 × 8 ft (4.9 × 2.4 m) English border in zone 6, part sun, seen from the path in mid July.
1. Bigleaf hydrangea 'Nikko Blue'14. Garden phlox 'Jeana'44. Garden phlox 'Jeana'44. Garden phlox 'Jeana'43. Coral bells 'Firefly'33. Coral bells 'Firefly'33. Coral bells 'Firefly'32. Green-and-gold22. Green-and-gold22. Green-and-gold23. Coral bells 'Firefly'33. Coral bells 'Firefly'33. Coral bells 'Firefly'33. Coral bells 'Firefly'33. Coral bells 'Firefly'32. Green-and-gold22. Green-and-gold22. Green-and-gold22. Green-and-gold22. Green-and-gold23. Coral bells 'Firefly'35. Siberian iris 'Caesar's Brother'55. Siberian iris 'Caesar's Brother'55. Siberian iris 'Caesar's Brother'54. Garden phlox 'Jeana'47. Easter lily77. Easter lily77. Easter lily78. Camassia88. Camassia88. Camassia83. Coral bells 'Firefly'33. Coral bells 'Firefly'33. Coral bells 'Firefly'33. Coral bells 'Firefly'33. Coral bells 'Firefly'36. Columbine meadow rue66. Columbine meadow rue66. Columbine meadow rue66. Columbine meadow rue66. Columbine meadow rue66. Columbine meadow rue66. Columbine meadow rue66. Columbine meadow rue62. Green-and-gold22. Green-and-gold22. Green-and-gold22. Green-and-gold22. Green-and-gold22. Green-and-gold22. Green-and-gold22. Green-and-gold22. Green-and-gold22. Green-and-gold22. Green-and-gold22. Green-and-gold22. Green-and-gold22. Green-and-gold22. Green-and-gold22. Green-and-gold27. Easter lily78. Camassia88. Camassia8
From above, to scale. Each circle is one plant, as wide as the room it needs.

The plants

  1. 1 Bigleaf hydrangea 'Nikko Blue' × 1, blue
  2. 2 Green-and-gold × 24, yellow
  3. 3 Coral bells 'Firefly' × 14, red
  4. 4 Garden phlox 'Jeana' × 4, pink
  5. 5 Siberian iris 'Caesar's Brother' × 3, purple
  6. 6 Columbine meadow rue × 8, lavender
  7. 7 Easter lily × 4, white
  8. 8 Camassia × 5, blue

Why this plant

  • The only bold leaves here. The rest are medium and fine. A change of leaf keeps plants distinct when nothing is in flower.
  • The bed's only structure. Shrubs and grasses keep their shape when the perennials die down, and it is the only one here.

Why here

  • Anchors a back corner. At 5 ft it is the tallest plant here, and the tallest close the ends of the bed, where they stand in front of nothing.
  • A step in the back row. Next to garden phlox 'Jeana' (4 ft): no two neighbours there are the same height, so the back steps up and down like a skyline.
  • One plant, alone. A shrub is seen as an object, and needs clear ground around it.

Why now

  • In flower for 7 weeks. From late June to early August.
  • In company. With coral bells 'Firefly', garden phlox 'Jeana' and Easter lily in mid July: 4 kinds at once.

Planned as an English border: 9 of the 9 groups (100%) are drifts, longer along the bed than they are deep. The bed is balanced: the left half carries 50% of the visual weight and the right half 50%. The bed is tied together by its repeats: four kinds come round again along it, among them green-and-gold and coral bells 'Firefly'.

The planner's own design check: 10 Excellent, 7 Good.

Open this bed in the planner Change its size, the sun or the style, move plants about, or swap one for another.

Where bigleaf hydrangea 'Nikko Blue' goes in a border

At 5 ft it belongs at the back of a bed. In the planner's ten height classes it is tall (4 to 5 ft).

Its job: anchor. A shrub that gives the bed permanent structure. Planted singly, as soon as the front edge is laid; everything else is arranged around it.

It flowers only on old wood, so a hard winter or a spring pruning costs a year's flowers. In mild, coastal gardens nothing matches its colour.

  • Blue mopheads in mild climates
  • Seaside gardens
  • Drying

What to plant with bigleaf hydrangea 'Nikko Blue'

Plants recorded as good partners for it, and what each pairing does:

  • Hosta: its green leaves are a setting for the flowers, before and after; spires rising out of its mound; low enough (18 in) to stand in front of it.
  • Japanese forest grass: its green leaves are a setting for the flowers, before and after; fine leaves against its bold ones; low enough (18 in) to stand in front of it.
  • Autumn fern: its dark green leaves are a setting for the flowers, before and after; medium leaves against its bold ones; low enough (22 in) to stand in front of it.

Questions about bigleaf hydrangea 'Nikko Blue'

Does bigleaf hydrangea 'Nikko Blue' need sun or shade?

Bigleaf hydrangea 'Nikko Blue' grows in part sun (4 to 6 hours of sun, including some afternoon sun) and part shade (2 to 4 hours of sun, mostly in the morning).

It wants soil that stays evenly moist, rich in organic matter, and plenty of water.

What zones does bigleaf hydrangea 'Nikko Blue' grow in?

USDA zones 6 to 9. It is hardy to zone 6, which means it survives winter nights down to about 0 °F (−18 °C).

Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.

When does bigleaf hydrangea 'Nikko Blue' flower in my zone?

In zone 5 it flowers late June to early August. As a summer flower it moves about half a week for every zone: earlier where it is warmer.

Roughly when bigleaf hydrangea 'Nikko Blue' is in flower
Zone 6Late June to early August
Zone 7Late June to early August
Zone 8Late June to early August
Zone 9Mid June to late July

Worked out from Hopkins' bioclimatic law: spring arrives about four days later for each degree of latitude north, and one zone is roughly two degrees. A warm spring or a cold one moves any garden two weeks either way.

How far apart should bigleaf hydrangea 'Nikko Blue' be planted?

4 ft (120 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 5 ft (150 cm), so a group knits into one patch.

It grows 5 ft (150 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.

How many bigleaf hydrangea 'Nikko Blue' plants do I need?

Usually one. At 4 ft (120 cm) across, it is a plant you place, not one you mass. For a hedge or screen, set them 4 ft apart: three plants for a 10 ft run.

In the bed above, the planner used one in one group.

Is bigleaf hydrangea 'Nikko Blue' poisonous to dogs and cats?

Yes: mild toxicity to people, dogs, cats and horses. Leaves and buds can cause vomiting and diarrhoea if eaten.

Rated from NC State Extension and the ASPCA. Where references disagree, the more cautious rating is used.

Is there a pet-safe plant like bigleaf hydrangea 'Nikko Blue'?

These come closest to doing what bigleaf hydrangea 'Nikko Blue' does, and no toxicity is recorded for them:

  • Purple beautyberry: the same job in a bed and the same flowering time; 12 in shorter, pink, not blue.
  • Summersweet: the same job in a bed and the same flowering time; 20 in taller, white or pink, not blue.

Matched the way the planner's Swap button matches plants: the same job in a bed, then size, then flowering time.

Do deer eat bigleaf hydrangea 'Nikko Blue'?

They may. NC State does not list it as resistant to deer or rabbits. Where they visit, protect it, or plant it among ones they avoid.

What flowers after bigleaf hydrangea 'Nikko Blue'?

Bigleaf hydrangea 'Nikko Blue' is over by early August. These start as it finishes and carry the same spot on, so it never goes flat:

  • Japanese anemone: from mid August to early October, 3 ft tall, to stand in front of it and cover its fading stems.
  • Lilyturf: from early August to mid September, 16 in tall, to stand in front of it and cover its fading stems.
  • Hosta 'Guacamole': from early August to late August, 24 in tall, to stand in front of it and cover its fading stems.

What does bigleaf hydrangea 'Nikko Blue' look like in winter?

Bigleaf hydrangea 'Nikko Blue' drops its leaves and stands as bare branches. That is when to see its shape, and to prune it if it needs pruning.

More Hydrangea

In these guides

Zone guides: Zone 6 · Zone 7 · Zone 8 · Zone 9

In flower in: June · July · August

Every fact on record

Type
Shrub
Size
5 ft (150 cm) tall, 5 ft (150 cm) wide
Plant
4 ft (120 cm) apart
Height class
Tall (4 to 5 ft)
Place in the bed
Back
Flowers
Late June to early August; dense clusters; blue, pink
Leaves
Bold texture, deciduous; green
Shape
Rounded, clumping
Hardy in
USDA zones 6 to 9
Light
Part sun, part shade
Soil
Rich, evenly moist
Water
High
Feeding
Moderate, in spring
Family
Hydrangeaceae
Comes from
Japan, China, Korea and Southeast Asia
Stands up to
Salt

Checked against NC State Extension and ASPCA poison lists. Flowering times are for zone 5: later in colder zones, earlier in warmer ones. Toxicity and spread information is a general gardening guide, not veterinary or medical advice, and invasive status varies by region. If a person or pet eats a plant, contact poison control or a vet. Check your local invasive species list before planting anything with a spread warning.