Vervain is a perennial erect herb, reaching up to 120 cm in height, with flowering and fruiting periods from June to October. Vervain is not particular about soil conditions, prefers fertile soil, fears waterlogging, and is not drought-tolerant. It can grow in most soils. However, it thrives best in deep, fertile loam and sandy loam, and is not suitable for low-lying, waterlogged areas. It commonly grows along roadsides, slopes, streamsides, or forest edges at low to high altitudes.