How to Grow Oenothera
From the Greek oinos, wine, and thera, pursuing or imbibing, the roots of one plant being thought to induce a thirst for wine (Onagraceae). A genus of 80 species of annuals, biennials and numerous good herbaceous and shrubby perennials for the herbaceous border and rock garden, natives of America and the West Indies, but now widely naturalized in many parts of the world. The flowers, fragrant in many species, are fragile in appearance, carried in racemes or singly in the leaf axils and generally yellow but there are white, pink and red forms. The common name, Evening Primrose, relates to 0. biennis in particular, the flowers opening in the evening.
Species cultivated 0. acaulis, trailer, flowers white, ageing to rose, spring to autumn, hardy perennial. 0. biennis, biennial, 3 feet, yellow, very fragrant, June-October. 0. erythrosepala (syn. 0. lamarckiana), 4 feet, flowers yellow, ageing to reddish, to 3.5 inches across, summer to autumn, probably of garden origin. 0. fruticosa, about 2 feet, lemon-yellow flowers, July and August, one of the best of the herbaceous perennials. 0. glaber, 1.5 feet, foliage bronze-green, flowers golden-yellow, summer. 0. missouriensis, about 9 inches, trailing and spreading in habit, bright, light yellow flowers, July, perennial. 0. odorata, to 1 feet, flowers yellow, turning red, to 2 inches across, opening in the evening, April to June, perennial; var. sulphurea, taller. later flowering, leaves, buds and stems tinted red. 0. perennis (syn. 0. pumila), 1 foot, flowers yellow, opening in daylight. July, perennial. 0. speciosa, 2 feet, white flowers, scented at night, appearing throughout the summer and early autumn, perennial, United States, Mexico. 0. tetragona (syn. 0. youngii), 2 feet, flowers yellow, to 1 inches across, opening by day, summer; var. riparia, 1.5 feet, flowers larger. Cultivars: ‘Fireworks’, 1.5 feet, bright red buds opening to yellow flowers, makes a very good plant for the front of the border; ‘Yellow River’, 1-1.5 feet, canary yellow, very free-flowering.
Cultivation These plants are sun lovers; they do well in any ordinary soils, including those that contain much chalk. The trailing kinds are suitable for the rock garden, taller kinds for sunny borders. They can be propagated by division in spring Or they may be grown from seed. Seed of the biennial species is best sown in May or June where the plants are required to flower, the flowers being produced the following year in July and August. Cuttings can also be taken of the perennial species in May and rooted in a sandy compost.