Oenothera biennis provides a wonderful splash of summer colour in the garden. Flowering begins in June and plants continue growing throughout the season so there is a constant succession until about September.
Commonly known as Evening Primrose, in early summer the sweetly scented, bright yellow flowers open towards evening and are faintly phosphorescent.
This introduced and widespread naturalised, although apparently decreasing wild flower, has a bright nectar guide pattern, invisible in visible light, but apparent under ultraviolet light, which assists pollination by moths, butterflies and bees.
The fragrant flowers are mostly fertilised by twilight-flying pollinating insects, along with moths and bats. Later in the season the flowers open all day but not have a scent until the evening. The seeds are also a good food source for birds.
Officially introduced in 1614 into Europe, during the 17th century, the Evening Primrose herb was called the 'King's cure-all' by herbalists, it was considered a panacea for treating most ailments. Today, many modern herbalists use an extract in cough remedies and the seeds are used to produce evening primrose oil. Over the last 20 years, the oil has once again become popular for its medicinal properties, and is now a common dietary supplement.
The whole plant is edible: the leaves can be cooked as greens, and the nutty-flavoured roots can be boiled and eaten like potatoes, parsnips, or salsify. The flowers make an especially lovely salad garnish.
In an article that appeared in 'Horticulture' magazine, Carol Bishop Hipps provided an evocative description of evening primrose in action:
“Watching an evening primrose bloom rekindles one’s sense of wonder. As fireflies drift aloft in the summer twilight, a tightly rolled up flower bud shaped like an okra pod begins to swell until it resembles a small yellow cigar. Suddenly the sepals flick back, the ghostly pale petals begin to spring apart, and the eight stamens and the cross-shaped stigma writhe into position. Bud after bud perceptively stirs, then flares open in a performance reminiscent of time-lapse photography. A rich fragrance fills the air, summoning night-flying moths, some of which hover like hummingbirds above the fragile, cup-shaped blossoms, probing for nectar.”
Sowing: Sow in spring or in autumn.
Seeds can be sown indoors in pots in spring or autumn and transplanted after the last frosts or can be sown directly where they are to grow after the final frosts in early summer.
When growing indoors, sow the seed thinly in pots containing seed starting compost. Press seeds in lightly, do not cover the seeds with soil as they need light to germinate. Make sure the compost is kept moist but not wet.
Seeds germinate in 15 to 30 days at 18 to 21°C (65 to 70°F). Transplant to individual pots when seedlings are large enough to handle and plant outside when rosettes are at least 7cm (3in) across. If planting in full sun area pick a cloudy day so plants have time to adjust to their new surroundings before the full sun hits them.
In outdoor beds, once the seedlings have developed two pairs of true leaves, thin out the weakest seedlings. Space seedlings or thin plants to 45cm (18in) apart. Grow in full sun and plant out in spring after all frosts. Water in well until plants have established then they can be ignored.
Evening Primrose is a hardy plant that does best on poor soils provided they are well drained. It does best in sandy soil but will tolerate almost anything that is not too wet. It prefers a position in full sun but will grow well in areas where it can get sun part of the day. It will not grow in shade. Once established the plants are extremely drought resistant and will continue to flower during hot dry periods.
No care or maintenance is needed once plants are growing just cut down the stems at the end of the flowering period. Plant may reseed themselves but need to be in areas where they are not disturbed to develop for the following year. If intending to allow reseeding be aware of the rosettes and don't weed out. If mowing keep blade high to miss the low growing rosette.
Herbalists consider the leaves together with the stem bark, flowers and seed oil to be the valuable parts. They have been used in the treatment of gastro-intestinal disorders, whooping cough and asthma. A tea made from the roots is also used in the treatment of obesity. Many modern herbalists use an extract in cough remedies. Culpeper said "as fine a salve to heal wounds as any that I know".
The herb was not examined closely until 1919, when the gamma linolenic acid (GLA) content was reported in Germany. Nowadays Evening Primrose Oil is extracted from the seeds, which contain two essential fatty acids: gamma-linolenic acid (GLA) a rare essential fatty acid that the body does not manufacture and the relatively common linoleic acid (LA). Both GLA and LA are said to aid in the reduction of pain and inflammation. Taken internally, the oil is said to have an effect in lowering blood pressure and in preventing the clumping of platelets, it has been recommended in treating cirrhosis of the liver and is most commonly taken for premenstrual problems.
Every part of this plant can be used. The leaves can be cooked and eaten as greens. The roots are edible if collected during the first year before the plant blooms. They can be boiled like potatoes and allegedly taste like sweet parsnips.
The flowers are sweet and can be used in salads or as a pretty garnish. The young seedpods can be steamed and the ripe seeds can be roasted in an oven and used on bread or in salads. You can also sprinkle the roasted seeds over any dish like pepper.
It is likely that Oenothera biennis, Evening Primrose, which is a North American native, was exported to Europe in the 1600's when cargo ships bringing cotton over, dumped the soil brought back as ballast and written descriptions of it began appearing. The plant was officially introduced in 1614 into Europe, and rapidly became known as ‘Kings Cure All’ because of its useful medicinal properties. It is now naturalised all over Europe.
Identification can be confusing because there is a large amount of variation within several very similar species in this genus. Growing in open disturbed areas such as fields, pastures, gardens, roadsides, and waste places. It prefers to grow in dry gravelly or sandy soil.
Evening primrose is a member of the Oenothera genus, containing familiar plants such as gaura and willow herb.
The generic name Oenothera is derived from the Greek oinos meaning 'wine' and thera meaning 'a hunt' (ther, meaning 'wild animal'.) Named by Theophrastus, the roots were used in scenting wine. They were soaked in wine and eaten as olives are now.
Folklore is rather contradictory: It was believed that eating the roots would enable the consumer to tame wild beasts, also eating the roots was believed to increase a person's appetite for wine. It also says that evening primrose counters the effects of drinking too much wine.
Native American Hunters are said to have rubbed the root on the soles of their moccasins to mask their smell and get closer to the animals.
As a Magick Herb, Evening Primrose is known as the 'Herb for a successful hunt'. Sew a small sachet out of muslin and fill it with the root of the evening primrose plant. If you don't hunt then try taking it with you when you go shopping for bargains.
The species name biennis simply refers to this plant being biennial. Biennial plants complete their life cycle in two growing seasons, usually growing root stocks and leaves in the first season and blooming and fruiting in the second.
Although it is commonly called Evening Primrose, the plant is a a relative of willow herbs and not primroses. In early summer the flowers open only at dusk. The bright yellow, fragrant flowers are mostly fertilised by twilight-flying insects, especially in the early season. Later in the season the flowers open all day but not have a scent until the evening.
Other names include Cureall, Fever plant, Field primrose, Four-o'clock.
The flowers represent fickleness or contrariness in the Victorian language of flowers.
The petals emit a phosphorescence at night, from this probably comes the German name of 'Gemeine Nachtkerze', meaning Common Night Candle.
Phosphorescence in Flowers:
Frederick Pursh the botanist made an interesting comment about the flowers of Evening Primrose:
"frequently observed a singularity in this plant, it is that in a dark night, when no objects can be distinguished at an inconsiderable distance, this plant, when in full flower, can be seen at a great distance, having a bright white appearance, which probably may arise from some phosphoric properties of the flowers." (King's American Dispensatory , Felter and Lloyd, 18th Edition, 1898).
Phosphorescence is, in some cases the mechanism used for 'glow-in-the-dark' materials which are 'charged' by exposure to light. In simple terms, it is a process in which energy absorbed by a substance is released relatively slowly in the form of light.
Phosphorescent materials store absorbed energy for a longer time, as the processes required to re-emit energy occur less often. Commonly seen examples of phosphorescent materials are the glow-in-the-dark toys, paint, and clock dials that glow for some time after being charged with a bright light such as in any normal reading or room light. Typically the glowing then slowly fades out within minutes, or up to a few hours in a dark room.
It was theorized that the flower are unusually visible at night because they are slightly phosphorescent and able to produce, as it were, their own light so as to attract pollinators.
- Additional Information
Packet Size 1 gram Average Seed Count 3,000 Seeds Seed Form Natural Common Name Evening Primrose, Herb Primrose, King's cure-all
Wildflower of Europe
Other Common Names Suncups, Sundrops, Kings Cure-All, Night Candle, Fever Plant, Night Willow Herb, Field Primrose. Family Onagraceae Genus Oenothera Species biennis Synonym Onagra biennis, Brunyera biennis, Oenothera muricata Hardiness Hardy Biennial Flowers Pale yellow, June to October Height 90–120cm (36-48in) Position Full sun preferred Soil Sandy soil Time to Sow Sow in early//late spring and late summer/autumn. Growing Period Start in early spring or in autumn to bloom the following year. Notes Hardy to minus 23°C (-10°F)