Rhododendron transiens ("Oyamatsutsuji")

Japanese name: オオヤマツツジ （大山躑躅）
Scientific name: Rhododendron transiens

[Overview]
A semi-evergreen shrub 1–2 m tall, found in open woods in hilly areas.
Young branches and petioles are densely covered with brown bristles.
There are two types of leaves, spring leaves and summer leaves, both simple and alternate.
Spring leaves are ovate-narrowly elliptic to narrowly elliptic, 2–5 cm long and 0.8–2.5 cm wide, with a pointed tip; long hairs grow on both surfaces and the margins, especially densely on the veins of the underside.
Summer leaves are oblong to oblanceolate, 1.5–3 cm long and 0.5–1 cm wide, with a pointed tip.
The petiole is 0.1–0.3 cm long.
2–3 flowers are borne at the branch tips.
The flowers are reddish purple, 5–5 cm across, and the corolla is funnel-shaped with 5 lobes.
There are dark spots on the inner surface of the upper side of the corolla.
The flower color varies from strongly reddish to strongly purple.
There are 10 stamens.
The fruit is a capsule rather densely covered with long brown hairs.

[Cultivation]
Propagate from seed.
Cuttings are also possible, although the rooting rate is very poor.
It prefers sunny, well-drained, moisture-retentive, fertile, acidic soil.
Avoid dry sites, or use mulch or similar to keep the base of the plant from drying out.
For potted plants, it is best placed from spring to autumn in partial shade out of the afternoon sun and direct summer sunlight, and from autumn to spring in a sunny spot sheltered from cold wind; in the ground, a place shaded by deciduous trees is good.
For potted plants, from autumn to spring water thoroughly when the soil surface dries, and in midsummer water twice, in the cool of morning and evening, wetting the leaves as well.
For plants in the ground, rainfall is sufficient except in summer; in summer water in the cool of morning or evening, wetting the leaves as well, and in winter, if dry weather continues, water in the morning on a warm day.
Apply fertilizer three times in total, in winter, after flowering as a thank-you fertilizer, and in autumn, placing organic fertilizer or a slow-release chemical fertilizer with equal amounts of the three components around the plant.
Do not prune; limit care to bud thinning in early summer after flowering to tidy the shape.
Remove spent flowers promptly.
Pests include spider mites, azalea lace bugs and Benimon-aoringa.

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