Oenothera albicaulis Pursh
Whitest Evening Primrose, White-stem Evening Primrose, Whitish Evening Primrose, Prairie Evening Primrose
Anogra albicaulis, Oenothera ctenophylla
Bloom Time: Mid spring until the early fall
Oenothera albicaulis is an annual plant with an erect stem that grows up to 1.5 feet (45 cm) tall. Basal leaves are up to 2 inches (5 cm) long and can be either entire and oblanceolate or pinnatifid, even on the same plant. Flowers have four white petals that become pink with age.
It is grown as an annual plant, so it has no USDA hardiness zone.
How to Grow and Care
Oenothera plants can be propagated by dividing established clumps in spring or fall. Softwood cuttings may be struck in late spring. Easy to grow Oenothera seeds can be sown directly in the garden in late summer, early fall, or planted early in the spring.
Just cover the tiny seeds, and germinate at 65 to 70 °F (18 to 21 °C). Seeds require darkness to break dormancy. Space plants 5 to 9 inches (13 to 23 cm) apart. Plant in light, well-drained soil with a pH of around 5.5 to 7.0. Sandy soil works well for this plant.
Oenothera is tolerant of dry and is a good candidate for xeriscaping. The foliage can be robust in really fertile soil, but fewer flowers form. Top dress with fully composted manure in the spring. Provide irrigation during long hot spells, and cut the plants back by a third after flowering to keep them looking neat. Hot summer weather may cause the plants to briefly stop flowering. Powdery mildew sometimes appears in humid conditions.
See more at How to Grow and Care for Oenothera.
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