Japanese name: イワガサ（岩傘） Scientific name:Spiraea blumei var. blumei
[Overview]
A deciduous shrub 1–1.5 m tall, growing on rocky, gravelly ground in mountains and along the coast.
The branches are often arched.
Young branches are green to brown and almost hairless.
The leaves are alternate, 1.5–3.5 cm long and 1–3 cm wide, obovate to rhombic-ovate, sometimes 3-lobed, with irregular, notched teeth.
The veins on the upper surface of the leaf are slightly sunken.
The petiole is 0.3–1 cm long.
The leaves and petioles are almost hairless.
Corymbs at the branch tips bear about 20–30 white 5-petaled flowers.
There are 20 stamens, about as long as the petals.
The fruit is a follicle.
[Cultivation]
Propagate by division or cuttings.
It prefers sunny, well-drained soil.
For potted plants, water thoroughly when the soil surface dries; for plants in the ground, rainfall is sufficient unless summer brings a long spell of sunny weather and the soil becomes severely dry.
Apply organic fertilizer in winter, and after flowering place slow-release fertilizer on the soil as a thank-you fertilizer.
Flower buds form in autumn, so if pruning, do it as soon as possible after flowering.
Pests and diseases include powdery mildew and scale insects.
