Begonia grandis (hardy begonia, "Shukaido")

Japanese name: シュウカイドウ （秋海棠）
Scientific name: Begonia grandis

[Overview]
A perennial found in damp places in partial shade to shade.
It forms tubers (bulbs) underground.
The stem is 40–60 cm tall, erect and branching in the upper part, green, soft and hairless, with reddish nodes.
The leaves are simple and alternate, 8–15 cm long, heart-shaped and slightly asymmetrical left to right.
The leaf margins are serrated.
The flowers are borne in cymes, hanging down on long stalks, and are pale pink.
There are male and female flowers, with the male flowers on the upper part of the stem and the female flowers on the lower part.
The male flower consists of 2 petal-like sepals and 2 smaller petals, and the female flower consists of 2 petal-like sepals and 3 petals.
The female flower has an ovary with 3 wings, so its base is shaped like a triangular pyramid.
The fruit is a capsule with 3 wings, one of which projects out much larger than the others.
Many seeds are produced, but they rarely germinate under natural conditions.
In autumn, bulbils (asexual buds) that form in the upper leaf axils of the stem fall to the ground and become new plants.

[History]
It was introduced as an ornamental plant in the early Edo period (around 1620–1640) and has become naturalized.

[Cultivation]
Propagate by bulbils or leaf cuttings.
It cannot be increased by the tubers.
The seeds are small and hard to germinate.
It prefers a damp, partially shaded site with soil that is airy, well drained and moderately water-retentive.
Plant the tubers shallowly, so that they are just lightly covered.
Strong sunlight causes leaf scorch, and the plant weakens if it dries out.
If the environment suits it, it grows well even when left alone.
Watering is not particularly necessary for plants in damp spots in the garden; otherwise, water thoroughly when the soil surface dries.
In winter the aboveground part dies back and the plant goes dormant, so leave it as it is without any winter protection.
Thrips can occur.

[Notes]
The Japanese name derives from the fact that it flowers in autumn and the flower color resembles that of Kaido.

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