Evening primrose has plenty of admirers thanks to its beautiful and delicate appearance, but just as many people view this fiesty floral as an invasive and temperamental weed. Native to North America, the flower is best sown in early spring or late fall, will grow quickly and bloom each summer, beginning during its second year of life.
Evening primrose self-seeds, so it's possible that, unless properly trained and cared for, it could easily take over your garden. Still, its sunny yellow flowers can lure many gardeners with their beauty. The plant is nocturnal, meaning its blooms open in the evening and close throughout the day, attracting a different set of nighttime pollinators, such as moths and some bees.
|Botanical Name||Oenothera biennis|
|Common Name||Evening primrose, common evening primrose, tree primrose, fever plant, cure-all, night willow-herb|
|Plant Type||Herbaceous perennial|
|Mature Size||3–5 ft. tall, 2–3 ft. wide|
|Sun Exposure||Full sun, partial shade|
|Soil Type||Moist but well-drained|
|Soil pH||Neutral to acidic|
|Bloom Time||Summer, early fall|
|Hardiness Zones||4–9 (USDA)|
|Native Area||North America|
|Toxicity||Toxic to dogs and cats|
Evening Primrose Care
If the invasive nature of evening primrose doesn't deter you (not to mention that you'll be asleep while its beautiful blooms are out), then you're in luck, because even the most 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.
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. It was first discovered by Native Americans, who used the plant to treat wounds and skin ailments (such as sunburn or eczema), and later on by Europeans who relied on it for a variety of issues like asthma, whooping cough, and more. 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. The flowers themselves are also edible both raw or cooked and are sometimes used in salads.
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 where 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, it 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 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 the summer, evening primrose actually prefers to be cool rather than warm. The plant needs to get established (i.e. grow its roots and foliage) during the cooler early months of spring in order 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 wild plants growing along the roadside or in public gardens. Once you get evening primrose seeds, plant them either in autumn or early spring 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 one foot apart.
In its first year of life, evening primrose will not flower but will simply produce a leafy rosette at ground level. Come year two, 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 one 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.
Common Pests and Diseases
Varieties 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 mealybugs, spider mites, and aphids. If you notice signs of infection on your plants, treat them with insecticidal soap or an oil such as neem oil.