Common evening primrose (Oenothera biennis) has plenty of admirers thanks to its beautiful and delicate appearance, but just as many people view this feisty floral as an invasive and temperamental weed. Native to North America, the flower is best sown in late fall, will grow quickly and bloom each summer, beginning its second year of life. Fragrant, four-petaled flowers bloom above a basal rosette of leafy branched stems.
Evening primrose self-seeds, so it's possible that unless properly cared for, it could easily take over your garden. Still, its pretty, lemon-scented yellow flowers can lure many gardeners with their beauty. The plant's blooms open in the late afternoon and evening and close throughout the day, attracting a different set of nighttime pollinators, such as moths and bats.
|Common Name||Evening primrose, common evening primrose, fever plant, cure-all|
|Botanical Name||Oenothera biennis|
|Plant Type||Herbaceous, biennial|
|Mature Size||3–5 ft. tall, 2–3 ft. wide|
|Sun Exposure||Full, partial|
|Soil Type||Moist but well-drained|
|Soil pH||Neutral, acidic|
|Bloom Time||Summer, fall|
|Hardiness Zones||4-9 (USDA)|
|Native Area||North America|
Evening Primrose Care
If the invasive nature of evening primrose doesn't deter you (not to mention that you may be asleep while its beautiful blooms are out), then you're in luck, because even novice gardeners can grow this herbaceous perennial. As long as you give it plenty of light and well-draining soil, chances are your evening primrose plants will be more than happy.
Though evening primrose doesn't require deadheading, controlling the plant is much easier if you snip or pinch off the expired blossoms to prevent the plant from self-seeding. Be sure to discard the spent flowers instead of letting them fall to the ground.
Evening primrose can grow rapidly and has been deemed an invasive species in some areas. Take care when planting evening primrose in your garden, as you'll need to keep a close eye on it to prevent spreading.
Contrary to what you may believe about a plant that only blooms at night (making it perfect for moon gardens), evening primrose actually loves sunlight. It should be grown in a spot that gets full sunlight (or partial shade) and somewhere that the plant can soak in at least six to eight hours of warm sunlight daily.
Another major requirement for growing evening primrose successfully is soil that boasts good drainage. That being said, the soil should still retain moisture, just not become water-logged. Consider adding a thick layer of mulch atop the soil to help keep the roots cool throughout the summer. Evening primrose can grow well even in rocky, sandy soil.
Evening primrose does best with adequate regular watering and will need a bit more water if grown in an especially hot climate during the summer. However, if you notice any discoloration or browning on the plant's many leaves, that's a sure sign that your evening primrose is getting too much water and is likely suffering from root rot or a fungal disease.
Temperature and Humidity
While it blooms and grows best during late summer, evening primrose actually prefers to be cool rather than warm. The plant needs to get established with roots and foliage during the cooler early months of spring to flower well come summer. Too much heat early on in its life can cause the plant to become leggy or resemble a weed in appearance.
Fertilizer is not a necessary addition to your evening primrose care regimen—it will grow just fine without the additional nutrients. However, if you are working with particularly bad soil, you can amend your mixture with some organic material.
How to Grow Evening Primrose From Seed
Evening primrose is typically grown from seed and, although you can buy the seeds online, you can just as easily collect seeds from large colonies of wild plants growing along the roadside. (Always use caution when foraging along roadways and ensure that you are not trespassing.) Once you get evening primrose seeds, direct sow them in autumn in a location that boasts full sun where the soil has been previously cultivated. Sow the seeds on top of the soil and water well. After germination, thin the seedlings so that they are approximately 1 foot apart. The seeds need a cold period, called stratification, in order to germinate. If you sow seeds indoors, use a small container filled with moistened seed-starting mix, sow the seeds on top of the soil, cover, and place in the refrigerator to mimic a natural chilling period. Take out in late winter to pot up the plants when they have two sets of true leaves.
In its first year of life, evening primrose will not flower but will simply produce a leafy rosette at ground level. During the second year, a tall, stiff flower stem shoots up out of this base. About midway up this flower stem, secondary branching occurs, and the leaves become progressively smaller the farther you go up the flower stem. The four-petaled blooms that begin emerging at the start of summer are about 1 inch wide. They'll eventually die off and produce seeds, which are then spread throughout the landscape by various weather conditions or eaten by wild birds.
Varieties of beetles eat the leaves of evening primrose, but they won't do enough damage to kill the plant. Otherwise, you can expect to see various other traditional garden pests periodically, including leafhoppers, lygus bugs, and aphids. If you notice signs of infection on your plants, treat them with insecticidal soap or a diluted oil such as neem oil.
Common Problems with Evening Primrose
Though evening primrose is a rather easy plant to grow and manage, it will sometimes show a few problems.
Decaying or Wilting
This is often the result of bacterial soft rot, which occurs at temperatures between 70 and 80 degrees Fahrenheit and affects plants that are sitting in soggy soil or very humid conditions.
Yellowing Foliage and/or Stunted Flowers
Fungal diseases are known to limit the plant's ability to take up water and nutrients, leading to yellowing of the leaves, stunted flowers, and root rot. Pull these flowers up and discard them to prevent the fungus from moving to other plants.
Discoloration of Foliage and Flowers
This can be caused by gray mold, which can cover the plant with fuzzy gray and brown spots. This happens even as the plant slowly succumbs to the resulting lack of nutrients. Pull the plants to prevent the spread.
Is evening primrose a medicinal plant?
Beyond being a beautiful, vibrant addition to your garden or landscape, evening primrose plants have a storied history in the medicinal community; some of the common names for the plant, such as cure-all or fever plant, allude to these holistic properties. These days, it's most commonly seen as an herbal supplement or oil and used for skin disorders, as well as pain issues related to diseases like multiple sclerosis and rheumatoid arthritis.
Is evening primrose edible?
The roots, shoots, and seeds of evening primrose are edible.
How long can evening primrose live?
Primrose self-seeds readily, so a set of plants can easily come back in the garden again and again for several years.
Common evening-primrose. Invasive Plant Atlas of the United States.
How to Use Mulching and Avoid Overwatering in Summer Vegetable Gardens. University of Nebraska-Lincoln.
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Signs and symptoms of plant disease: Is it fungal, viral or bacterial? Michigan State University Extension.
Gray mold in the flower garden. University of Minnesota Extension.
Supplements for Pain. U.S. Department of Veterans Affairs.
Chung, Bo Young, et al. Effect of Evening Primrose Oil on Korean Patients With Mild Atopic Dermatitis: A Randomized, Double-Blinded, Placebo-Controlled Clinical Study. Annals of Dermatology, vol. 30, no. 4, 2018, pp. 409–16, doi:10.5021/ad.2018.30.4.409
Majdinasab, Nastaran, et al. The Effect of Evening Primrose Oil on Fatigue and Quality of Life in Patients with Multiple Sclerosis. Neuropsychiatric Disease and Treatment, vol. 14, 2018, pp. 1505–12, doi:10.2147/NDT.S149403
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