COMMON EVENING PRIMROSE - Oenothera Lamarckiana is an herbaceous annual that has naturalized throughout the United States. Primrose Evening seeds can be started directly outdoors in spring or fall, and Oenothera Lamarckiana produces richly scented, two inches across, light yellow flowers that open in the late afternoon and remain open through the evening. Evening Primrose starts to bloom in late spring and blooms continuously throughout the summer, attracting bees, moths, and butterflies. 500+ seeds per order. Oenothera Lamarckiana. Annual. Full sun. Spring. Soil temp 65F+. SOW- 2/3 seeds per, 1/16" deep, about 18"apart. Keep moist. Germination 14-30 Days. Medium water. Height 18-24" x 18" wide. Flowers are yellow. Blooms early to mid-summer.