White Evening Primrose Oenothera berlandieri 'Siskiyou'

Evening Primrose is a low growing, flowering biennial, or herbaceous perennial with an upright habit in the primrose family and native to eastern and central Canada and the United States. 'Siskiyou' is a long-blooming and easy-care cultivar of Evening Primrose that can form a dense mat of lance-shaped leaves. Evening Primrose produces a basel rosette of leaves in its first year, but no flowers. In following years, the plant produces single, sometimes multiple, 2 foot stems topped by fragrant, white to pink flowers that open at dusk and close when hit by the morning sun (hence the common name, Primrose). However, at the southern end of its range, this species of primrose has been known to open its flowers in the morning and close them at dusk. The genus name may come from the Greek words oinos and theras meaning wine-seeker in reference to the use of the roots in scenting wine, but this is not proven.

'Siskiyou' Evening Primrose grows best in full sun, in average, well drained soil with dry to medium moisture. Although it will tolerate light or afternoon shade, it blooms better in full sun and heat. It will also tolerate some drought and will do well in gravelly or sandy soil. To encourage blossoms, remove spent flowers and fertilize in spring with rose food.

Flowers release their scent starting at dusk. In Mexico, the plant is known to blossom when temperatures are above freezing. In more northern parts of its range, the plant blooms heaviest during spring, with blossoms diminishing in size as the weather gets hotter. In both cases, each flower lasts only a single day.

The plant is resistant to damage by deer. Plants die after setting seed, but it is stoloniferous and may spread aggressively in the landscape by self-seeding or spreading roots in a somewhat weedy fashion. To avoid problems, you can plant primrose in areas where it can spread without intruding on other plantings.

Diseases, Insect Pests, and Other Plant Problems:

No known insect or disease problems. Leaf spot and powdery mildew, slugs and aphids may occur.