Evening Primrose (Oenothera biennis)

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Evening Primrose (Oenothera biennis)

Common Names 

Herb Primrose, King’s Cure-All, Wildflower of Europe, Cureall, Fever Plant, Field Primrose, Four-o’clock, Suncups, Sundrops, Night Candle, Night Willow Herb


About This Plant


Evening Primrose is a tall, wildflower-type biennial plant that is hardy in USDA zones 4-10. In its first year, many obtuse leaves are formed which spread into a flat rosette on the ground, and in its second year hairy, flowering stems rise to a height of three to four feet, sometimes more.  It flowers for a long time, making it very showy in the garden when planted in mass. 


Evening Primrose’s lemon-scented leaves are alternate, rough and hairy, and lanceolate with nearly entire margins. The second-year leaves are three to five inches long and one or more inches wide. The plant begins flowering in June and continues growing throughout the season, producing a constant succession of flowers until about September.  The sweetly scented, bright yellow flowers open in the evening time and emit a faint phosphorescent, earning it the German name of “Gemeine Nachtkerze” meaning Common Night Candle. The flowers can be seen at a distance on a dark night, having a bright white appearance. The blooms are produced all along the stalks, on the axillary branches, and in a terminating spike. The topmost flowers bloom first in early summer and as the stalks continue advancing in height new blooms form until Fall. The flowers are about 2 ½” wide, are a fine bright yellow in color, and are delicately scented.  The flowers open quickly in the evening, kind of like watching a slow-motion movie, and typically fade by mid-morning. They usually open between six and seven o’clock – hence the name “Evening Primrose”. The flowers are visited by a variety of moths including hawkmoths in the night which feed on the nectar, pollinating the flowers in the process.  Pollinated flowers form a one-inch-long oblong capsule filled with tiny reddish seeds. Birds like to eat the seeds. As a biennial, once the plant sets seed, it fades and dies. The plant forms an elongated taproot about the width and appearance of a parsnip. It is yellowish on the outside and white within. Small animals like to eat the roots and leaves of younger plants. Deer tend to graze on the older plants.


Evening Primrose is native to North America and can be found naturalized on river banks and other sandy places, such as waste areas, meadows, beaches, dunes, and roadsides.  The plant was first introduced to Italy in the early 1600s before being carried all over Europe. By the 17th century, it was well-known among herbalists and considered a panacea for treating many ailments, earning it the name “King’s Cure-all”. Its species name,”biennis”, means “two years” and indicates its biennial nature. ”Primrose” means “first Rose” and “Evening” was added to the common name a few centuries ago in reference to its habit of blooming in the evening. The plant is well-loved by many, herbalists in particular, but also is treated with disdain among many who view it as an invasive, fiesty floral. 




Evening Primrose seeds can be planted directly in the ground in the Fall or Spring.  The seeds need to experience a cold season (WInter) before they’ll germinate, so if planting them in the Spring, be sure to stratify the seeds first.  Seeds can be planted an inch deep if directly seeding them outdoors – less deep if starting them indoors. Germination should take place in about 15-30 days in 65-70 degree Fahrenheit soil temperatures. Evening Primrose can also be propagated from cuttings taken in the Spring or late Summer. 




Seedlings can be transplanted once the rosettes are at least three inches across. Transplant or thin seedlings to about one foot apart.  If planting seedlings into a full sun area, transplant on a cloudy day so that the plants have some time to adjust.  Take care to not disturb the root when transplanting as it can grow deep into the soil. 




Evening Primrose needs lots of light and will not tolerate much shade. It does best in poor, rocky, and sandy soil but will tolerate most soils as long as they are well-draining.  Once established, it is extremely drought resistant and needs no additional care.  It will self-seed and continue to grow in an area even though the biennial plants themselves will die off after two years. Evening Primrose actually prefers to be cool rather than warm and needs to get established, growing its roots and foliage, during the cooler early months of Spring in order to flower well in the Summer. Too much heat early on will cause the plant to become more leggy and weedy in appearance. Discoloration and browning of the leaves usually indicate the plant is getting too much water and that the soil needs better drainage. If allowed to self-seed, a few plants will turn into a large colony within a few years. The seeds can remain viable in the soil for 70 years. 


Seed Harvest


Evening Primrose seeds are mature and ready to be collected when the seed capsules begin to split open, usually around October. 


Plant Uses


  • Moon gardens
  • Meadows, wildflower gardens, and naturalized areas
  • Medicinal
  • Culinary


Culinary Uses


The entire Evening Primrose plant is edible and was a staple food source for many Native American tribes. The taste may be an acquired one, however.  The plant can irritate the throat of some people, even once cooked, so try all parts carefully and sparingly at first. 


The early leaves can be cooked as greens or used in tea. It is advised to cook the leaves in several changed of water in order to get rid of their bitterness, though they may remain tough and gritty.  The roots are nut-flavored and can be boiled and eaten like potatoes. They taste somewhat sweet and peppery.  Roots are typically harvested late in the first year or in the spring of the second year when they are sweet, succulent, and somewhat fleshy. If eaten raw, they will irritate the throat. Flowers and flower buds can be eaten raw or cooked and make a lovely salad garnish.  Second-year stalks can be peeled and eaten.  Young seedpods can be served steamed.  Mature seeds can be roasted and sprinkled on salads or on baked goods as a substitute for Poppy seeds.  To roast the seeds, rotate and press the dry seed capsules to release the seeds. Roast in the oven on a shallow tray for 15 to 20 minutes at 350 degrees.


Medicinal Uses


During the 17th century, Evening Primrose was called the King’s Cure-All by herbalists and it was used as a panacea for treating most ailments.  Native Americans used the whole plant for treating bruises and used its roots for treating hemorrhoids. Its use isn’t nearly as widespread today, but modern herbalists still use the plant in cold remedies and in the treatment of whooping cough and asthma as well as in the treatment of GI disorders. 


Most focus these days is on the amazing qualities of Evening Primrose’s seeds which are used to produce Evening Primrose oil. As well as being a great source of the amino acid tryptophan, which our bodies convert to the mood-improving brain chemical serotonin, the seeds also are a great source (7-14% total content) of the Omega-6 fatty acid GLA or gamma-linolenic acid. GLA is a very valuable fatty acid that is not found in many plants. It is used by the body to regulate blood pressure and to keep the immune system functioning well. It is reported to help with eczema rheumatoid arthritis, premenstrual syndrome, breast pain, menopause symptoms, ADD, asthma, migraines, heart disease, high cholesterol, inflammation, multiple sclerosis, and diabetes as well as diabetic neuropathy. Evening Primrose was not examined closely by scientists until 1919 when the GLA content was reported in Germany. The oil has once again gained popularity in the last 20 years and is now a common dietary supplement (creating a nearly two hundred million dollar market annually). The oil has a short shelf-life of about six months and should be kept refrigerated to keep from growing rancid. 


Evening Primrose and its oil is considered safe for use by most people. It may cause headache or upset stomach in some people, so the oil should not be taken on an empty stomach. People with bleeding disorders and those with surgeries planned within the next two weeks should not take it as it may increase the risk of bleeding. It also might increase the risk of seizures, especially in those who are prone to them. 




Evening Primrose is native to North America.


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