Hydrangea macrophylla ‘Nikko Blue’ is a classic garden favorite known for its brilliant clusters of blue blooms and lush green foliage. This mophead hydrangea produces large, rounded flower heads from early to late summer, creating a soft, elegant display that brightens shady garden corners and borders. The flowers open as rich sky blue in acidic soil and shift to soft pink in more alkaline conditions, offering a natural variation in tone that adds depth to the landscape. Each cluster can reach up to 6 inches across, supported by sturdy stems that rise above dense, dark green leaves with a slightly glossy finish.

Beloved for its timeless beauty and reliability, ‘Nikko Blue’ makes an excellent focal point in foundation plantings, along pathways, or as a showy addition to cottage and woodland gardens. It also performs beautifully in containers, where its long-lasting flowers can be enjoyed up close.

‘Nikko Blue’ hydrangeas thrive in partial sun to filtered shade, preferring morning light and protection from the harsh afternoon sun. Plant in rich, moist, well-drained soil with a preference for slightly acidic conditions to achieve the signature blue blooms. Keep the soil consistently moist, especially during hot weather, and mulch around the base to help retain moisture and regulate temperature. Pruning should be done right after flowering, as this hydrangea blooms on old wood; cutting back too late in the season may remove next year’s flower buds. Fertilize in early spring with a balanced or acid-forming fertilizer to encourage healthy growth and vibrant blooms.

Growth Habit

This deciduous shrub typically grows 4 to 6 feet tall and wide, forming a full, rounded shape. Its large flower heads and rich foliage create a lush, layered appearance that looks equally stunning in mass plantings or as a single specimen. The flowers age gracefully, turning greenish or lavender as they dry, extending their beauty well into autumn.

Like most hydrangeas, all parts of ‘Nikko Blue’ are considered toxic if ingested by pets or humans, due to naturally occurring compounds that can cause stomach upset. However, it is generally left alone by deer and rabbits, making it a low-maintenance and dependable choice for ornamental planting.