Bigleaf hydrangea (Hydrangea macrophylla 'Nikko Blue') hy-DRAIN-jah mak-roe-FIL-lah Genus:  Hydrangea

This is a well-loved and vigorous cultivar with large, rounded flower heads of a rich, gorgeous blue.

Noteworthy Characteristics: 

This is one of the most widely recognized species of hydrangeas, and boasts a plentiful number of cultivars. The species is divided into two groups: the Hortensias (or "mopheads") have globe-shaped flowers made up of large male flowers, and the Lacecaps have flattened flower heads, with central, female blossoms ringed in larger, male blossoms. 

Care: 

'Nikko Blue' flowers on the previous season's wood, and can be maintained by cutting back just to the first pair of buds beneath the old flower in spring.  Grow in moist, but well-drained soil, in sun to partial shade. Provide shelter from drying winds.

Propagation: 

Sow seed in cold frame in spring; take softwood cuttings in early summer, hardwood cuttings in winter.

Problems: 

Gray mold, slugs, powdery mildew, rust, ringspot virus, leaf spots.

Overview

Height 3 ft. to 6 ft. Spread 6 ft. to 10 ft. Growth Habit Clumps Growth Pace Moderate Grower Light Full Sun to Part Shade Moisture Medium Moisture Maintenance Low Characteristics Showy Flowers, Showy Seed Heads Bloom Time Summer Flower Color Blue Uses Beds and Borders, Container, Cut Flower Style Cottage Garden Seasonal Interest Summer Interest Tolerance Frost Tolerant Type Shrubs