Evening Primrose

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Common Name

Evening Primrose, Sundrop

Scientific Name

Oenothera Biennis

Plant Category

Biennial, perennial

Location

North and South America, Britain

Height

6-24 inches

Width

2-5 inches

Blooming Season

Late spring to early fall

Plant Habit

Low-growing

Color

Yellow, white or pink

Sun

Full sun

Soil

Acid, neutral and basic (alkaline) well-drained soil

Water

Moderate

Plant Characteristics

Fragrant flowers. Edible and medicinal. Drought-resistant.

Usage

Used in rock gardens, wildflower meadows and naturalistic borders and along the edges of roads and trails.

Information

The plants are very tall, often 4 to 5 feet or more in height. Their stems are erect, stout, soft-hairy, reddish and branching forming a shrub. Leaves are alternate, rough-hairy, lanceolate, about 3 to 6 inches long and lemon-scented. The taproot is elongated, fibrous, yellow on the outside and whitish within. The flower spikes grow on auxiliary branches all along the stalk. They are about 2-1/2 inched in diameter, bright yellow and have four petals, a cross shaped stigma and a refluxed calyx (leaves under petals). The plants have a fairly short bloom period.  The flowers open in the evening and close up during the day and are strongly scented with a delicious sweet perfume which attracts pollinating moths. The fruit is an oblong 1 in. capsule containing many tiny reddish seeds.

Growing Tips

Evening primroses do best in sunny locations with well-drained soil. Dig one large hole to accommodate several plants or plant in individual holes. A light application of organic fertilizer should be added to the planting hole for best results. Plants should be positioned no deeper than they were growing in containers. Plants should be spaced 1 to 2 feet apart. The plants should be watered weekly throughout the first summer, until they are established. Water established plants only during dry summers. Apply a light application of dry organic fertilizer to the top of the soil in spring.

Common Problems

No serious insect or disease problems. Root rot may occur in wet, poorly drained soils. Weed control needs to be carried out at establishment. Evening Primroses are slow to germinate, so it is important to reduce initial competition from weeds using herbicide. They grow best in low fertility conditions. Too much fertilizer can encourage weed growth.