Green Neighbors Program

The Clark County Green Neighbors Program was developed and is maintained by Clark County Solid Waste and Environmental Outreach to assist citizens with developing more sustainable lifestyles and building a strong environmental community in Clark County. Solid waste regional planning and programs are a cooperative effort of Battle Ground, Camas, Clark County, La Center, Ridgefield, Vancouver, Washougal, and Yacolt. Funding for this project provided by a grant from the Washington State Department of Ecology.

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Evening Primrose

  • Scientific Name: Oenothera biennis
  • Garden: Beneficial Insects and Compost Garden
  • Plant Type: Herbaceous Biennial
  • Evergreen/Deciduous: Evergreen
  • Sun/Shade Exposure: Full Sun
  • Moisture Requirements: Moist, Well-Drained

Plant Information

Easily grown in average, medium moisture, well-drained soils in full sun. Tolerates some part afternoon shade and some drought. Grows well in gravelly or sandy soils. May spread in the landscape by self-seeding in a somewhat weedy fashion. In the first year, this biennial typically produces a basal rosette of shallow-toothed, lanceolate, light green to olive green leaves (to 4-8” long and 2” wide) but no flowers. In the second year, a stiffly-upright, rough-hairy, purple-tinged flower stem (usually a single stem but sometimes multiple stems) with spirally arranged leaves rises from the center of the rosette to 3-5’ tall, topped by a showy summer to fall (June to September) bloom of bowl-shaped, four-petaled, lemon yellow flowers (each to 1-2” across). Flowers bloom in a multi-flowered terminal panicle and, if present, in panicles at the tips of major stems, with a single flower blooming at the base of upper leaf-like bracts. Flowers open at dusk and close again in the morning when hit by sun, hence the common name of evening primrose. Flowers are fertilized by night-flying moths which are attracted by the mild lemon flower fragrance and by bees in the early morning before closure. Each flower has 4 petals, 4 reflexed sepals, 8 stamens and a prominent style with a cross-shaped stigma. Fruits are capsules (narrow seed pods to 1 1/2” long) which split open when ripe to release numerous seeds (to 100 seeds per capsule). Plants die after setting seed but will remain in the landscape through self-seeding. No serious insect or disease problems. Leaf spot and powdery mildew may occur.

Data Source

Photo Credit

OEBI flower Pleple2020 (©2020 Pleple)
About the Master Gardeners Natural Gardens
The demonstration gardens are meant to show different ways to practice earth-friendly techniques at home. There are eight beautiful backyard example gardens that fit any yard size or preference.
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