What Is Hydrangea Serrata?

Hydrangea serrata is a deciduous flowering shrub of medium size native to east Asia. It is widely used as a landscape and garden plant in many countries. Common names for Hydrangea serrata include mountain hydrangea, blood-on-the-snow, and tea of heaven. This hydrangea is a close relative of the better known large leaf hydrangea, Hydrangea macrophylla. Flowers, stems, and leaves are smaller on Hydrangea serrata, but it is a hardier species and can be planted in areas too cold for Hydrangea macrophylla.

A spot with well-drained, fertile soil is ideal for this shrub. It does best in partial shade, but will tolerate full sun if the soil is not allowed to dry out. Hydrangea serrata reaches a height of 3 to 5 feet (about 1 to 1.5 m) and usually is as wide as it is tall, growing into a round mound. It can grow up to 18 inches (about 45 cm) a year in favorable conditions. The dark green leaves are oval-shaped, up to 6 inches (about 15 cm) long, and have a toothed, or serrated, edge which gives the species its name.

Hydrangea serrata flowers are actually clusters of florets and are shaped like snowballs or lacy caplets. Sterile and fertile florets are mixed in the clusters, and the sterile ones are slightly showier. Flower color depends on the acidity of the soil where the plant is growing. In very acid soil the blossoms are blue, while in more alkaline places they bloom in shades of pink. Some flowers may be white, or white shading into blue or pink.

Within its native range of east Asia and Japan, Hydrangea serrata grows in cooler areas up to 5,000 feet (1,524 m) above sea level. In North America it is usually recommended for USDA plant hardiness zones 6 and 7, but can be planted as far north as zone 5 if it is provided with adequate winter protection. Following particularly cold winters flowers may be sparser than usual. It has been successfully grown as far south as parts of zone 9 when planted in a shaded area and given plenty of water.

Hydrangea serrata blooms mostly on old wood, the stems that grew in earlier years. To encourage best blooming the only routine pruning should be removal of dead or damaged stems. It is a summer flowering shrub, and the blossoms are most profuse in July and August. The flowers are pollinated by insects.

Hydrangea serrata, commonly known as mountain hydrangea, is a species of flowering plant native to the mountainous regions of Korea and Japan. It differs from other hydrangeas in its smaller size, more compact foliage, and the serrated edges of its leaves, which give the plant its name. It's also known for its hardiness and ability to withstand colder climates.

Yes, Hydrangea serrata can change color based on soil pH. Acidic soils can produce blue flowers, while alkaline soils tend to yield pink flowers. This color change is due to the presence of aluminum ions in the soil, which are more available to the plant in acidic conditions. Gardeners can adjust soil pH with additives to alter the flower color.

Hydrangea serrata thrives in well-drained, moist soil and partial shade. It's best to water it regularly, especially during dry spells, and apply a layer of mulch to retain soil moisture. Pruning should be done immediately after flowering to encourage new growth and blooms for the following season. Protecting the plant from harsh winter winds can also be beneficial.

Ideal growing conditions for Hydrangea serrata include partial shade, as too much sun can scorch the leaves, and protection from strong winds. The soil should be rich, moist, and well-draining with a pH that can be adjusted to alter flower color. It prefers cooler climates and can tolerate temperatures down to USDA zone 6.

Hydrangea serrata can be susceptible to common hydrangea pests and diseases such as aphids, mites, powdery mildew, and leaf spot. Good cultural practices, such as proper spacing for air circulation and avoiding overhead watering, can help prevent these issues. Infected plants should be treated early with appropriate fungicides or insecticides.

Adding Hydrangea serrata to a garden offers aesthetic benefits with its beautiful and variable flower colors. It's also a relatively low-maintenance plant that can provide a backdrop for other perennials or serve as a focal point in a shade garden. Its ability to attract pollinators like bees and butterflies is an added ecological benefit.