Orostachys japonica (rock pine, "Tsumerenge")

Japanese name: ツメレンゲ （爪蓮華）
Scientific name: Orostachys japonica

[Overview]
A perennial 8–30 cm tall, found on sunny rocks and on roofs.
The leaves are simple, alternate and fleshy, and are of 2 types; the rosette leaves are lanceolate, 2.5–6 cm long and 0.5–1.5 cm wide, often tinged with crimson in winter, with a needle-like projection at the tip.
The rosette leaves produced in winter are smaller than the summer leaves.
The leaves on the stem are lanceolate.
From the center of the rosette rises a tower-shaped flower stalk 8–30 cm tall, bearing a conical inflorescence.
The inflorescence has lanceolate bracts.
The flowers are white, 5-petaled, about 1 cm across, and open in a star shape.
There are 10 stamens, and the anthers are reddish purple.
The fruit is a follicle.
The plant dies after fruiting, but increases by producing offsets.

[Cultivation]
Propagate by division.
It prefers a sunny site with well-drained sandy soil.
Potted plants should be kept in a well-ventilated place out of the rain during long rainy spells.
For potted plants, in spring and autumn water thoroughly a few days after the soil has dried; water sparingly in midsummer and withhold water in winter.
For plants in the ground, rainfall is sufficient.
Poor ventilation or excess moisture can cause root rot and gray mold.
Fertilizer is not particularly necessary.
Offsets form, but if the parent plant flowers, they may flower together with it and die, so if you wish to increase the plants, separate them from the parent early.
Pests and diseases include gray mold and scale insects.

View this page in Japanese (日本語)