Japanese name: アイ（藍） Scientific name:Persicaria tinctoria
[Overview]
An annual 50–90 cm tall, cultivated since ancient times.
The stem branches well in the upper part.
Leaves are simple and alternate, ovate to lanceolate.
Pseudoracemes at the stem tips bear dense flowers.
The flowers have no corolla, and the pale pink calyx is conspicuous.
The fruit is an achene.
[History]
Since before the Common Era it has been used as a source of indigo dye in many parts of the world.
It was introduced to Japan from China in the Nara period.
It is still grown today in places such as Tokushima.
[Uses]
Besides being made into indigo dye, the leaves and fruits are used medicinally.
[Cultivation]
Propagate from seed, by division, or from cuttings.
It prefers a sunny, well-drained site.
For potted plants, water thoroughly when the soil surface dries; for plants in the ground, rainfall is sufficient.
Apply slow-release fertilizer as a base fertilizer, and it is also good to give liquid fertilizer once or twice a month during the growing season.
There are no particular pests or diseases.
