What is an Evening Primrose?

Learn more about the evening primrose including its characteristics, growing conditions, and its essential uses. We've included tips on how to grow these adorable plants that are a vibrant addition to ornamental or herb gardens.

Beautiful cluster of bright yellow evening primrose flowers in bloom in the evening sun

Oenothera Biennis

We are very pleased to introduce you all to the common evening primrose. Part of the genus oenothera, oenothera biennis (syn. oenothera muricata), is a proud member of the primrose family with a very unique quality.

The common name, evening primrose, is very descriptive of this unique quality, which is that this flower blooms at night. This attracts entirely different types of pollinators to the plant.

Some other common names include; evening star, sundrop, weedy evening primrose, German rampion, hog weed, King’s cure-all, or fever-plant.

These last nicknames may sound odd, but they come from the plant’s significant medicinal benefits that saved many lives in the early 1800’s. But more on that later!

This marvellous flowering plant is simultaneously beautiful, prosperous, and medicinally beneficial, while at the same time being temperamental and invasive. If you are not fearful of dynamic plant life, then read on to discover if the evening primrose will be the next member of your green space.

Amazing wild evening primrose flower spike blooming at dusk with wild blue flowers in the background

Table of Contents

Related: Sun-Loving Flowers | Water-Loving Flowers | Shade-Loving Flowers | Types of Flowers | Types of Flowers by Color | Types of Flowers by Alphabet | Types of Flower Colors | Yellow Flowers

What does an Evening Primrose Look Like?

Flowers

Everybody recognizes a primrose. These lovely specimens bloom from the early spring to the late summer at the end of a long flower stem.

Evening primrose flowers are hermaphroditic, meaning that they possess both male reproductive characteristics and female reproductive characteristics. Each flower has 8 stamens and a cross shaped stigma.

Blooms are comprised of 4, bilobed petals. Petals are yellow in color and have a very distinct nectar guide pattern. This is a specific flower pattern that is only visible to the human eye under ultraviolet light. This is actually how pollinators, like bees, moths, and butterflies, see all the time!

As we mentioned before, evening primrose is interesting because flowers will only open once the sun has started to go down. This creates a gorgeous spectacle at dusk. This also means that they attract completely different evening pollinators.

Once pollinated, an evening primrose will produce fruit in the form of a seed capsule. Seed capsules contains numerous long seeds that are released once the capsule hardens and splits open at maturity.

Focus image of blooming evening primrose flowers with yellow petals and cross shaped anthers

Leaves

Evening primrose leaves are lanceolate in shape. A mature leaf will be between 3 and 7 inches in length, though leaf size and pattern changes throughout the life cycle of the plant.

Growth Pattern

The evening primrose is a biennial plant, meaning that it will experience its entire life cycle in 2 years, then die.

In the first year of growth, there will be no flower blossom. Instead, the plant will only produce a tight basal rosette of leaves that grows close to the ground.

In the second year of growth, a tall and stiff flower stem will emerge from the basal rosette. Half way up the stem there will emerge a secondary branch.

Along these branched stems, leaves will grow progressively smaller as they reach the top. At the end of the flowering stem will emerge the 4 bilobed petal yellow flowers.

Young basal rosette of leaves growing in sandy soil of the evening primrose plant

Where are Evening Primroses Native to?

Evening primroses are native plants to mostly central and eastern North America. More specifically, it can be found growing in Canada most eastward in Newfoundland and west to Alberta.

From here, the growing range dips into the United States, southeastward to Florida, and the southwestward to Texas.

These plants are resilient and prosperous, and have become naturalized in many other temperate and subtropical places around the world. They can exist in USDA zones 4 through 9.

When growing as a wildflower, they can be found thriving in arid, sunny locations like prairies or disturbed areas — usually about 700 metres above sea level.

Wild cluster of evening primrose flowers growing in a dry arid landscape of Utah with blue skies

How do you Propagate an Evening Primrose?

Now that we know the fundamentals about the evening primrose, it’s time to get down and dirty — literally in the dirt! This next portion we’ll talk about how to propagate your own evening primrose.

Be warned, this plant species is known as being invasive. This means that it can easily take over an area and sometimes cause detriment to other plant life.

Evening primrose self seeds, and if you’re not careful, it can very easily take over your garden. But that isn’t all too bad, as they are quite lovely after all.

Large young seed capsules containing multiple seeds of the evening primrose sitting on a wooden table next to bottle of evening primrose oil

Sow Seed

The best way to propagate your own evening primrose is by sowing seed. You can collect your own seeds either by purchasing them from a nursery, or collecting them along roadsides where they tend to grow vigorously.

It is best to sow seed either in the beginning of April, or later in the season, from mid July to mid August. They shouldn’t be started indoors and transplanted, as the roots are quite fragile.

Pick a spot on your property that receives full sun, and has well drained soil. Sprinkle a fist full of evening primrose seed on top of the soil.

These seeds require sunlight in order to germinate, so they can’t be buried deeply into the soil. They need to be in a sheltered place where they will be undisturbed during their germination period.

They will take 2-3 weeks for successful germination. Not much water is needed during this period of growth, and watering can sometimes dislodge the seeds!

Maintenance

Once 2 or 3 weeks have passed, evening primrose seedlings should start popping up. The sprinkled seed will have produced many specimens, so feel free to pull up certain seedlings so that each individual plant has about 12 inches of space. We don’t want them to feel crowded!

At this point, the plant will need moderate watering, especially if you live in a hot climate. Even though these plants tend to grow best in the summer, they prefer being cold!

Help your plant out by adding a nice, thick layer of mulch on top of the soil. This will help keep soil moist, and it will also help keep the roots of the plant nice and cool in the heat of the summer.

Lovely ornamental garden with large boulders surrounding a prosperous evening primrose patch of yellow blossoms

What are the Growing Conditions of Evening Primrose?

Soil Type

Though evening primrose can tolerate many different soil types, there are a couple things to keep in mind!

The main characteristic that the soil should have is proper drainage. This is the case with many plant species, but it is essential for the evening primrose.

When in the wild they tend to grow in loamy soil, so try to imitate that if you can! Additionally, if you have exceptionally low nutrient soil, feel free to incorporate it with compost to help raise the nutrient content.

Water Level

Evening primrose requires moderate levels of water. Most of the time natural precipitation will be sufficient, though not if you live in a particularly hot climate.

Take care not to over water your plant as well, as they are particularly susceptible to root rot or fungal diseases (like powdery mildew) due to over watering. Leaf browning is a sure sign that your specimen is receiving too much water.

Sun Exposure

Though it may seem contradictory – since the evening primrose only blooms in the evening – but these are a sun loving plant!

Ensure that they have the opportunity to grow in an area that receives a minimum of 6 hours of full sunlight per day. They are completely tolerant to partial shade, especially in the heat of the afternoon.

Focus on striking bright yellow flower petals of the evening primrose with new seeds about to disperse

Temperature

The temperature preference for the evening primrose can be rather confusing. Though they grow most prosperously in the summer time, they actually prefer to be cool!

They can sometimes perish if a summer is too hot, so that thick layer of mulch we mentioned earlier can help out with that. These plants can exist in USDA zones 4 through 9.

Fertilizer

One low maintenance aspect of the evening primrose is fertilizing. They don’t actually need to be fertilized at all! However, if your land happens to have particularly low nutrient soil, feel free to mix in some compost to help boost the nutrient content.

Pruning

Okay. If there were an important detail to remember, this would be it: if you do not want your evening primrose to self seed, you must deadhead.

Deadheading is when you pinch off the flower head before it has the chance to go to seed. This is a nifty way to help control your flowering plant garden.

Otherwise, not much needs to be done in terms of pruning. These plants exhibit a very neat and tidy growth habit.

Intolerances

Though they aren’t the most low maintenance of all plants (not everything can be a cactus), even the most novice of gardener can successfully incorporate an evening primrose into their green space.

They must simply remember that the evening primrose is intolerant to water logged soil, intolerant to shade, and that’s about it! Easy!

Dew coated yellow petals of evening primrose flower growing at the end of a tall flower stem

How is Evening Primrose Used?

Wildlife Ecology

We don’t need to explain any further that the evening primrose makes for a lovely ornamental plant. Let’s get into the cooler uses.

Evening primrose seeds are a very vital source of food for various bird species. The plant is also the larval host for various night flying moths, like the primrose moth or the white-lined sphinx moth.

Like we mentioned before, since this plant blooms at night, that means that it is a source of nectar for an entirely different group of pollinators! Night pollinators include various bee, moth, and butterfly species.

Large honey bee visiting the just opened blossom of an evening primrose flower

Edible Plant

Hopefully after reading this article, those who were of the opinion that the evening primrose was a pesky and invasive weed may change their minds!

Nearly every single part of the evening primrose is edible. Starting at the roots, all the way up to leaves, flower buds, flower blossoms, and seeds of the plant.

Evening primrose roots can be cooked and eaten like you would a starchy vegetable (like a potato) or they can be eaten raw.

The leaves of the plant should be harvested before the plant has gone to flower. These can be eaten raw, like you would a salad green or an herb, or they can be cooked like you would kale or spinach!

Buds and flowers are often used as a colorful and mild tasting garnish, or they can be steeped as used as a digestive tea. Whether it be in salads or a hot drink, everyone should try what the evening primrose has to offer.

Medicinal Plant

The evening primrose plant was used as a medicinal plant by various indigenous communities long before it was ever recognized for its ornamental quality.

Cherokee, Iroquois, Ojibwe, and Potawatomi, are various North American First Nations communities who have used this plant both as a food crop and medicinal crop for many many decades.

Traditionally, this plant could be used as an herbal medicine to aid with internal ailments like fever and cough, as well as external ailments like skin wounds and eczema (atopic dermatitis). It’s even known to help toughen up brittle nails!

In modernity, evening primrose is taken medicinally in the form of evening primrose oil. Evening primrose oil is taken from the seeds of the plant.

Seeds contains a protein content of 15%, oil content of 24%, and cellulose content of 43%. The proteins are very rich in essential amino acids, such as cysteine, methionine, and tryptophan.

The reason why evening primrose oil is significant is because of gamma linolenic acid (GLA) which are polyunsaturated fatty acids. Linoleic acid is an essential fatty acid that is known to help reduce cholesterol.

Small bowl of evening primrose oil sitting on a wooden table next to cut flowers of evening primrose

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