Common Evening-primrose (Biennis)

The Common Evening-primrose (Biennis) is generally described as a biennial forb/herb. This is native to the U.S. (United States) has its most active growth period in the spring and summer and fall . The Common Evening-primrose (Biennis) has green foliage and inconspicuous yellow flowers, with an abuncance of conspicuous brown fruits or seeds. The greatest bloom is usually observed in the late spring, with fruit and seed production starting in the summer and continuing until fall. Leaves are not retained year to year. The Common Evening-primrose (Biennis) has a short life span relative to most other plant species and a rapid growth rate. At maturity, the typical Common Evening-primrose (Biennis) will reach up to 5 feet high, with a maximum height at 20 years of 0 inches.

The Common Evening-primrose (Biennis) is usually not commercially available except under contract. It can be propagated by seed. It has a moderate ability to spread through seed production and the seedlings have high vigor. Note that cold stratification is not required for seed germination and the plant cannot survive exposure to temperatures below -28°F. has medium tolerance to drought and restricted water conditions.

Uses of : Landscaping, Medicinal, Culinary, etc.

Ethnobotanic: The Cherokee, Iroquois, Ojibwas, and Potawatomi were among several Native American tribes that used common evening-primrose for both food and for medicinal purposes. The roots were boiled and eaten like potatoes. The young leaves were cooked and served as greens. The shoots were eaten raw. A tea was made from the plant and used as a dietary aid or stimulant to treat laziness and “overfatness.” A hot poultice made from the pounded roots was applied externally to treat piles and boils. A poultice made from the entire plant was used to treat bruises. The roots were chewed and rubbed onto the muscles to improve strength. The plant was used to treat pain associated with menstruation as well as bowel pain. Handfuls of people still use the plant today, medicinally and for food. Other: Common evening-primrose is commercially cultivated in over 15 countries for its oil which contains the essential fatty acids, linoleic acid and gamma linolenic acid (Kemper 1999). When the seedpods ripen, the tall stalks can be cut and used as interesting additions to dried arrangements.

Wildlife: Hummingbirds visit the flowers to obtain nectar and insects to eat. The seed capsules provide food for many other birds during the winter months. It is thought that the plants are pollinated by night-visiting hawk moths, which feed on their nectar. Japanese Beetles prefer the leaves of common evening-primrose to those of other garden plants.

General Characteristics

General: Evening Primrose Family (Onagraceae). Oenothera biennis is a biennial, herbaceous forb. The family is so-named because the flowers are partially to fully closed during the day and open in the evening. The bright yellow to gold corolla is 2-5 cm wide, with four petals. The fragrant flowers usually last only one to two days. The erect stem, which sometimes branches near the top, can be covered with hairs. The plant grows from 3-25 dm tall. Basal leaves, which form a rosette, are from 10-30 cm long. The stem has alternate, lanceolate-shaped leaves, 2.5-15 cm long, that are shallowly toothed and wavey at the edges. The leaves are usually hairy. The plant flowers can from June through October.

Required Growing Conditions

For current distribution, please consult the Plant Profile page for this species on the PLANTS Web site.

Adaptation Common evening-primrose grows in dry open fields, along roadsides, railroad embankments, waste areas and in open woods.


Weediness This plant may become weedy or invasive in some regions or habitats and may displace desirable vegetation if not properly managed.

General Upkeep and Control

OPAC"To keep the plants in bounds, cut off outermost joints. Prune in late spring or summer. Use tongs or rolled newspapers to grasp the stems while cutting with pruning shears. "

Plant Basics
Growth Rate Rapid
General Type Forb/herb
Growth Period Spring, Summer, Fall
Growth Duration Biennial
Lifespan Short
Plant Nativity Native to U.S.
Commercial Availability Contracting Only
Physical Characteristics
Bloom Period Late Spring
Displays Fall Colors No
Shape/Growth Form Single Crown
Drought Tolerance Medium
Shade Tolerance Intolerant
Height When Mature 5
Vegetative Spread None
Flower Color Yellow
Flower Conspicuousness Yes
Fruit/Seed Abundance High
Fruit/Seed Seasonality Summer Fall
Seed Spread Rate Moderate
Gardening Characteristics
Propagations (Ways to Grow) Seed
Moisture Requirements Medium
Cold Stratification Required No
Minimum Temperature -28
Soil Depth for Roots 10
Toxic to Nearby Plants No
Toxic to Livestock No
After-Harvest Regrowth Rate Slow
After-Harvest Resprout Ability No
Responds to Coppicing No
Growth Requirements
pH Range 5–7 pH
Precipitation Range 20–20 inches/yr
Planting Density 0–0 indiv./acre
Soil Textures Coarse, Fine, Medium
Soil Depth for Roots 10
Minimum Frost-Free Days 120 day(s)
Salinity Tolerance None
CaCO3 Tolerance Medium
Sustainability & Use
Leaf Retention No
Fire Resistant No
Causes Livestock Bloating None

Source: USDA, NRCS, PLANTS Database,
National Plant Data Center, Baton Rouge, LA 70874-4490 USA