Hydrangea macrophylla 'Nikko Blue' could be the bluest of the blue hydrangeas when planted in acidic soils. If the soil is alkaline, the summer flowers on this shrub will likely take on a delicate pinkish hue. Standing up to 6' at maturity, Hydrangea macrophylla 'Nikko Blue' makes a 'pop' in front of a fence line or when used as a specimen plant in a partly sunny spot. Feel free to get your fill of electric blue, and plant in mass for a wow-factor that will have human heads turning.