Ipomoea nil (Japanese morning glory, "Asagao")

Japanese name: アサガオ （朝顔）
Scientific name: Ipomoea nil

[Overview]
A twining annual cultivated mainly for ornament.
The whole plant is covered with many hairs.
The stem grows long and twines around other objects.
Leaves are alternate and simple, entire or lobed.
Flowers are borne in the leaf axils, usually funnel-shaped, opening in the morning and wilting by afternoon.
Flower color and form vary with the cultivar.

[History]
The place of origin is not clearly known, but is said to be Southeast Asia to the Himalayas.
It is presumed to have been brought to Japan from China as a medicine by the Japanese envoys to Tang China in the late Nara period to the early Heian period.
In the Edo period, variation in the shape and color of flowers and leaves became abundant, and it came to be grown widely in pots.
In particular, those called henka-asagao (variant morning glories) became a boom.
The mainstream today is the large-flowered asagao.

[Uses]
The seeds are used as a crude drug called kengoshi.

[Cultivation]
Propagate from seed.
It prefers sunny, well-drained soil rich in organic matter.
Seeds do not germinate at low temperatures, so sow them in May–June, when the temperature rises above 20°C.
The seed coat is hard, so make a small nick in the surface with a cutter or similar and soak the seeds in water for a day and a night; this makes the cotyledons open more easily. Take care not to make the cut too deep, and not to damage the white part called the hilum.
Keep the seeds watered so they do not dry out until germination.
After germination, transplant to the final position when 3–4 true leaves have appeared.
Pinching the tip of the vine produces side vines and gives more volume.
Water when the soil surface dries, but in midsummer water in the morning and evening when the temperature has not risen.
In addition to base fertilizer, give diluted liquid fertilizer about once a week after transplanting.
Aphids can occur.

[Notes]
The theory that the "asagao" in the Seven Herbs of Autumn refers to the Chinese bellflower (Kikyo) is the established view.

View this page in Japanese (日本語)