Evening primrose (Oenothera biennis) is a late summer-early autumn wildflower that is often seen in the eastern half of North America. The little biennial is a common resident of roadsides, barnyards and fallow fields. The arching stems grow up to 6 feet (2 meters) tall and the butter yellow blossoms open each evening and close when the sun hits them of the morning. It has a long bloom period, with flowers opening around a central axis at the tips of the branches for several weeks. In fact, folklore has it that the flowers open oriented to the four points of a compass, but that's not true. They do open around the central axis stem giving that appearance, but can open at any point in between north, south, east or west.
This plant was well-known to Native Americans and was used as both a food source and a medicine. The roots were either boiled or roasted and eaten much like a potato, while the leaves were added to soups and stews, or blanched and added to other dishes. Evening primrose is not toxic and in today's world, the flowers can be added to salads or used as dessert decorations. The seeds contain gamma-linoleinc acid, which is an essential fatty acid that the body does not produce. Oil of Evening Primrose is available commercially as a dietary supplement from a number of sources. The oil is purportedly a successful treatment for eczema and other skin irritations and the tea made from the leaves is supposed to ease childbirth pains. Bathing in water that contains evening primrose is supposed to reveal your inner beauty to potential love interests as well. Primroses are also associated with the Norse goddess Freya who symbolizes youth and love.
Oenothera biennis isn't picky about where it grows. As long as the area is sunny and not swampy, it finds a home, regardless of the soil fertility. It even seems to thrive along railway tracks and abandoned city lots. Plant it at the back of the border along with goldenrod, asters and joe pye weed for a natural, prairie look. Just remember, as with hollyhocks, the first year will only have the basal rosette and the second will produce the blooms. Evening primrose reseeds quite happily, so once it is established, there will always be plants in your garden. Direct seed in the fall or early spring since this plant does not take kindly to transplanting. The seeds are so tiny that mixing them with sand will help distribute them evenly across the planting bed. Just scatter them on top of the prepared ground and do not cover them They require light to germinate. Be aware that once established, it will reseed wherever they drop. Some people call it 'invasive', since it is hard to eradicate, however, since this plant is native, 'aggressive' is the proper term. Regardless, take note that babies will pop up in the vicinity with regularity.
This night-blooming flower attracts nocturnal insects to the nectar and it is a host plant for several sphinx moths. Bees, hummingbirds and other important pollinators visit them in the mornings before the flowers close. Gardeners wanting to create a moon garden should consider this plant too. The yellow flowers show up at night well and you'll be rewarded by the groups of insects...and bats hunting them. A win-win situation for gardener and wildlife alike.