Silene flos-cuculi (ragged robin, "Kakkosenno")

Japanese name: カッコウセンノウ（郭公仙翁）
Scientific name: Silene flos-cuculi

[Overview]
A perennial 30–80 cm tall, found in its native range in places such as moist pastures.
The stem has downward-pressed hairs.
The leaves are simple and opposite, oblanceolate to narrowly oblong, about 7 cm long and 1 cm wide, and spatulate on the lower part of the stem.
The leaf margins are entire.
The stem branches in the upper part and forms cymes, with flowers at the branch tips.
The flowers are 5-petaled, 3–4 cm across, reddish purple or rarely white, and each petal tip is deeply divided into 4.
The calyx tube is hairless.
The fruit is a capsule.

[Cultivation]
Propagate from seed or by division.
It also spreads readily from self-sown seed.
It prefers a sunny, well-drained, fertile soil with moderate moisture.
It dislikes heat and humidity, so in summer keep it in a cool place in partial shade; in the ground, it is best planted where it is shaded by deciduous trees in the afternoon.
For potted plants, water thoroughly when the soil surface dries; for plants in the ground, rainfall is sufficient.
Plants in the ground need no particular fertilizing; for potted plants, apply slow-release fertilizer in spring and autumn.
There are no particular pests or diseases.

[Notes]
The Japanese name was given because it blooms around the time the cuckoo sings.