Hugely popular - and deservedly so - Hydrangea macrophylla 'Nikko Blue' features large, rounded flower heads, up to 5 in. across (12 cm), densely packed with rich, deep blue florets. Blooming in early summer for up to 2 months, 'Nikko Blue' is very floriferous and produces new flower stems throughout the summer. The foliage is medium green with large, lustrous, serrated leaves. A classic name in mophead hydrangeas, it has become the standard against which other blue hydrangeas are measured.

• Vigorous, this deciduous shrub has a round habit, typically growing 4-6 ft. tall and wide (120-180 cm).
• A part shade lover, it is best grown in rich, medium moisture, well-drained soils. Full sun is tolerated if constant moisture is provided.
• No serious pest or disease issues. Watch for bud blight, bacterial wilt, leaf spot and mildew.
• Perfect from foundation plantings to container plantings. Massed in a sheltered location or as an accent plant. Effective as an hedge and makes excellent cut flowers too!
• Blue in acidic soils, the flowers turn pink in alkaline soils. To change their color, add aluminum sulfate to the soil to make the flowers bluer or add lime to the soil to make them pinker. Treatment should occur ahead of time (late fall or early spring).
• Remove spent flowers to promote new blooms.
• This beautiful deciduous shrub should be pruned after flowering by cutting back the stems to a pair of healthy buds. Prune out weak or winter-damaged stems in early spring.
• Hydrangea macrophylla species is native to Japan. It is reported from seaside habitats as well as mountains in Japan, from Honshu southwards. This species has naturalized in China, New Zealand and the Americas.
• May cause mild stomach upset if ingested, contact with foliage may aggravate skin allergies. Wear gloves and other protective equipment when handling.
• Toxic to dogs, toxic to cats, toxic to horses.