Hydrangea serrata var. serrata f. prolifera ("Shichidanka")

Japanese name: シチダンカ （七段花）
Scientific name: Hydrangea serrata var. serrata f. prolifera

[Overview]
A deciduous shrub.
It branches freely from the base, and the branches are slender.
The leaves are simple and opposite, oblong to ovate-elliptic, with triangular teeth on the margin.
The upper surface of the leaf is slightly glossy.
Cymose inflorescences are produced at the branch tips.
The inflorescence has sterile flowers around the edge and bisexual flowers in the center.
The sterile flowers have sword-shaped petals and are double, overlapping in a star shape.

[History]
It has been known since early times, to the extent that it appears in Siebold's Flora Japonica, but in Japan it was long thought to have died out.
However, it was rediscovered in 1959 (Showa 34) in the Rokko mountain range in Hyogo.

[Cultivation]
Propagate by division or cuttings.
It prefers partial shade and moist, fertile soil that is well drained and retains water well.
It tolerates shade, but flowers less freely.
It is unsuited to places where the soil becomes extremely dry or that receive strong afternoon sun.
It absorbs a lot of water, so for potted plants take care that they do not dry out, and water thoroughly when the soil surface dries.
Plants in the ground do not particularly need watering, but during the hot season in summer water them in the morning or evening when the temperature is low.
Apply organic fertilizer twice a year, in winter and before flowering.
Pests and diseases include powdery mildew, anthracnose, mosaic disease, leaf spot, scale insects and aphids.

View this page in Japanese (日本語)