The first Hydrangea macrophylla I learned as a plant science major, back in 1992, was Nikko Blue hydrangea.
That's not the only reason it's a classic - you'll see old big ones thriving in gardens throughout the Deep South and on Cape Cod and the Islands.
We mean what we say about seeing Big Ones. Nikko Blue isn't a small hydrangea for pots or squeezing in nooks and crannies. It's typically medium-sized at about 4-5' tall, probably because of occasional pruning. Keep in mind that it has the potential to grow to 6' tall when sited in a Happy Place (sheltered, well watered, some morning sun). I've seen a picture of a Nikko Blue slightly taller than a 6' tall person. It was impressive.
So, when siting Nikko, think about the possibility of impressive size for a bigleaf hydrangea and either give it enough space or keep in mind that you may have to prune it a bit if it gets too big. Pruning is not as scary as it seems - we've written articles to help you understand pruning in the "Gardening Articles" section.
Nikko Blue hydrangea is a tried-and-true blue/pink mophead (depending on soil pH), recommended for garden nostalgia and reliability in zones 7 through 9.
When blue, it's the classic (there's that word again) Cape Cod blue color.
Nikko Blue bigleaf hydrangea
bigleaf hydrangea, french hydrangea, mophead hydrangea, hydrangea, hortensia
USDA Hardiness Zones
flowering shrub, deciduous
- Spring: medium green
- Summer: medium green
Fall Leaf Color Quality
Soil Moisture Requirements
moist-but-draining, no standing water
Soil pH Requirements
acid, neutral, alkaline
sun, part shade, shade
To Make It Thrive
Give Nikko Blue rich soil and consistent moisture in a soil that drains. It may need extra watering, but doesn't like standing water.
Make sure NB has full shade or afternoon shade in the deep south (zones 8 and 9) not only for the foliage, but so the flowers don't get sun scald. Increasing amounts of sunlight is increasingly tolerable the further north one goes on the map.
Traveling northward, consider planting in warm sheltered locations, such as near heated buildings.
Here in zone 8a, we cover to protect flower buds during spring transition - the up and down temps cause flushes of growth that are then zapped by cold. Covering the growth with old terry cloth towels or thermal blankets generally works to ensure summer flowers.
Is 'Nikko Blue' remontant?
We're not sure. We've read statements saying it is remontant, but we have not experienced it reblooming. Maybe it is somewhat or unpredictably remontant? If you have any insight, we would love to hear from you. When do I prune?
Bigleaf hydrangea flowers on old wood, so if you need to prune, do so in the summer after flowering. See our blog posts about pruning