This genus consists of over 100 species of hardy annuals, biennials and perennials from North America, now grown widely in other parts of the world. In summer, a profusion of delicate flowers appears, releasing a beautiful fragrance mainly at night. The flowers are most commonly yellow, though white, pink and red are also seen. The trailing species are a good choice for rock gardens, while more shrubby varieties are useful for borders. Some species have become troublesome weeds in some coun�tries.

Species

O. acaulis is a trailing perennial, with white flowers, turning pink with age, through-out summer.

O. biennis, evening primrose, zone 4, is the main plant from which the pop�ular essential oil is extracted. This biennial produces fragile, yellow blooms, flowering and releasing its fragrance only in the evening. It grows to 1 m (3 ft) or more.

O. fruticosa, zone 4, is a perennial plant, to 60 cm (24 in), with rich yellow flowers. O. fruticosa subsp. glauca has a branching habit and pale yellow flowers from late spring to late summer. The leaves are usually gray-green, and the plant grows to 90 cm (36 in).

O. macrocarpa, a trailing peren�nial, to 15 cm (6 in), has bright yellow flowers, sometimes spotted in red.

O. perennis is a perennial, to 50 cm 120 in), with yellow flow�ers.

O. speciosa, white evening primrose, is an attractive, clump-forming perennial, bearing masses of pink-tinted, white flowers from summer to autumn. It grows 30-60 cm (12-24 in) high. The pink-flowered form 'Rosea' is popular in cottage gardens.

Cultivation

Plant in any garden soil in a sunny position. Most species grow from seed, while the perennial species are propagated from cuttings. Some species tend to be invasive.