Evening primrose or Oenothera, also known as suncups or yellow sundrops, adds a beautiful burst of color in the garden. With over 145 species, there are numerous variations and health claims.
Growing Evening Primrose
Evening Primrose | Genus: Oenothera
Evening Primrose Growing Guide
Herbaceous flowering plant
• Hardiness zones 3 to 9
• Full sun
• Light loam or sandy soil
• Some Oenothera flowers open just in evening, evolving with specific evening pollinators.
• Check your specific variety for any known aggressive reseeding or spreading.
Evening primrose (Oenothera) is one of many flowering perennials in my own cottage-style garden.
It started with a single plant and over just a few years has spread quite assertively in the sandy soil.
But, unlike horrific invasive plants that spread by root-runners deep in the soil, evening primrose is not hard to control.
If I want a wide swath of yellow, I leave it alone. If I want to reduce it, I both divide the plants and cut back the flowers after blooming (to prevent seeds from forming).
Many Different Evening Primrose Species
There are quite a number of Oenothera varieties (145 species), with different shapes and colors (yellow, pink, white). I am very fond of the Oenothera fruticosa with bold, yellow cup-like flower petals and orange-red stamens. The flower buds also have a gorgeous deep red color which stands out in the spring garden.
My interest is flowers is all about contrasting colors and textures in relation to the rest of the garden, and evening primrose is gorgeous next to other bold colors including deeper blue delphiniums.
Evening primrose oil (made from Oenothera seeds) is widely available in stores selling vitamins, minerals, and supplements. There are many health claims associated with the oil and I have discussed them further in the Frequently Asked Questions section below.
Oenothera Plant Facts & Growing Tips
|Common name(s)||Evening primrose, suncups, yellow sundrops|
|Origin||Mexico and Central America|
|Type||Annual and perennial varieties|
|USDA Zones||3 to 9|
|Height||Most grow 12 to 36-inches tall|
|Light||Full sun or close to it|
|Soil||Light loam or sand, well-drained|
|Flower times||Summer | deadhead or cutback after flowering|
|Colours||Yellow, pink, white|
|Pollinators||Moths, bees, insects|
|Propagation||Divide plants or sow seeds|
|Pruning / Cutting back||Cut back after flowering|
|Problems||Can be invasive or aggressive by seeds or spreading. Check before planting.|
May get powdery mildew or leaf spot.
|Trivia | Uses||Despite the common name evening primrose, they are not closely related to primroses (genus Primula).|
Many Oenothera flowers open in the evening, attracting vespertine bees that forage at that time of day.
There are many claims that evening primrose oil (a fatty acid) is effective in cancer treatments, acne prevention, relief of menstrual symptoms, eczema relief, hastening child birth labor (and more).
Find Your Frost Dates & Hardiness Zone
- Plant Hardiness Zones | United States | Canada
These are listed on seed packets and plant tags to guide your choices.
- Average Frost Dates | Use this calculator at Almanac.com. Enter your city and state or province to find your first and last frost dates and number of frost-free days.
Frequently Asked Questions
1 Is evening primrose invasive?
There are annual and perennial varieties and yes, some can be invasive or aggressive depending on the species and your growing conditions.
Here in southwestern Ontario, Canada, I find the roots require division each year as they expand rapidly. I also cut the plants back after flowering to stop them from producing and sowing seeds. Thankfully, it is easy to reduce or remove.
2Can I grow evening primrose in containers?
I think you can grow just about anything in a container so long as you have adequate root space, good potting mix, provide light and water as needed, and have suitable winter storage.
I keep various perennials in containers and put them in the shed or garage from fall to spring. A hand cart / hand truck makes it much easier to move them around.
3Do any creatures rely on evening primrose?
Yes, Schinia felicita and S. florida moths feed exclusively on the Oenothera genus.
Pollination is provided by various moths, bees, and insects, although the structure of the flower limits the number of capable pollinators.
Some evening primrose open their flowers in the evening and are therefore used by evening pollinators like moths.
4Do I need to prune evening primrose plants?
It’s not necessary for basic plant health but perennial varieties can be cut back after blooming to prevent the forming of seeds if you don’t want them self-seeding.
5What are the benefits of evening primrose oil?
Evening primrose oil—gamma-linolenic acid (GLA), an omega-6-essential fatty acid—is widely available as a supplement.
Some of the health claims purport it is beneficial in some cancer treatments, for resolving skin issues including eczema, psoriasis, and acne, diminishing inflammation in rheumatoid arthritis, and relief of gastrointestinal disorders including irritable bowel syndrome and peptic ulcers, and more. It was also rumored for years to help speed up childbirth labor. The list goes on and on.
If this interests you, I suggest diving into the research to see if any of these claims can be substantiated. I have no experience with any of it.
Happy gardening! And be sure to sign up for the free newsletter.
~Melissa the Empress of Dirt ♛