The evening primrose (Oenothera biennis) comes into its own at sunset. That's when the tall, flowering herb unfurls its clear yellow blossoms and scents the air with a haunting floral-citrus fragrance. Once limited to folklore remedies, evening primrose is now utilized for a number of healing purposes, most utilizing an oil made from its seeds.
Evening primrose is one of the taller flowering herbs, growing between 3 and 6 feet tall. As a seedling the leaves form rosettes, but in ensuing years the leaves branch from the main stem. The wavy, medium-green leaves are large at the base and grow smaller as they climb the stem in an alternating pattern, resulting in a pyramid shape. The pointed buds unfurl at sundown, revealing 3-inch, bright yellow cup-shaped flowers. The plant blooms from early summer into the autumn. Toward the end of the season, its long seedpods open, spilling small, round tan seeds onto the ground and usually making it unnecessary to replant in subsequent years.
Special nighttime gardens often include evening primrose because it blooms once the sun sets. Not only do its clear petals seem illuminated by the moonlight, but the blossoms also scent the air. In late summer, the flowers stay open during cloudy days, making them a useful plant for the back border of flower and herb gardens.
Evening primrose thrives in sunny gardens which don't retain excessive moisture. Either sow the seeds in the spring and thin to 12 inches apart, or set seedlings 12 inches apart in late spring. Tough plants that flourish in the wild, evening primroses don't require special fertilizers or watering schedules. In windy areas, staking may be needed.
The seeds of evening primrose contain the essential fatty acids known as GLA (gamma-linolenic acid) and LA (linoleic acid). The University of Maryland Medical Center points out that both LA and GLA are "good" sources of omega-6 oils, as opposed to the kind found in fatty foods. The medical center recommends those taking evening primrose oil balance those omega-6 oils with either a supplement of omega-3 oil or a diet rich in omega-3 oils, including salmon and other cold-water fish.
For home harvesting, the leaves and stems can be infused to make skin cream, or in facial steams. "The Complete Book of Herbs" recommends using the leaves as a tea to treat coughs.
An oil made from the seeds of the evening primrose has been used in holistic health care. The oil is often packaged into capsules, making it easy to control the dosage. The University of Maryland Medical Center recommends the supplement for rashes and eczema, breast pain and complaints related to premenstrual syndrome. It is often taken for other conditions, including arthritis, menopause, heart disease, multiple sclerosis, attention deficit disorder, asthma and breast cancer. Studies relating to evening primrose oil's effectiveness for specific complaints are ongoing.