Hydrangea serrata is a species of flowering plant in the family Hydrangeaceae, native to mountainous regions of Korea and Japan.

Growing to 1.2 m (4 ft) tall and broad, it is a deciduous shrub with oval leaves and panicles of blue and pink flowers in summer and autumn (fall).

With a rounded habit, it features dark green, serrated (toothed), ovate leaves to 15 cm (6 in) long, and clusters of long-blooming blue or pink lacy flowerheads in mid- to late summer.

The flowers are perfect, having both male and female parts; they are insect-pollinated.Hydrangea serrata is best grown in rich, medium moisture, well-drained soils in partial shade.

It may lose significant numbers of flower buds or die to the ground in harsh winters, impairing or decimating the bloom for the coming year.

Hydrangea serrata makes a good specimen or accent plant for protected locations near homes or patios.

Some susceptibility occurs to honey fungus, bud blight, bacterial wilt, leaf spot, and powdery mildew.