Water regularly during dry periods, especially when plants are young or flowering. Allow the soil to dry slightly between waterings.

Mature plants are relatively drought-tolerant once established, but consistent moisture promotes better blooms.

Deadhead spent flowers to encourage continuous blooming and prevent self-seeding if desired. In autumn, cut back the main stems to the ground after flowering or before winter dormancy.

This tidies the plant and prepares it for the next growing season.

Common evening-primrose is easily propagated by seeds sown directly outdoors in early spring or autumn. It also readily self-seeds. Division of established clumps in spring is another effective method for propagation.

Repotting is typically not necessary for Oenothera biennis, as it is a biennial or short-lived perennial often grown as an annual. If grown in containers and needing repotting, do so in spring before new growth begins.