Oenothera Species, Evening Primrose, Dandelion-Leaved Sundrop

Oenothera acaulis

Family: Onagraceae (on-uh-GRAY-see-ee) (Info)
Genus: Oenothera (ee-no-THEE-ruh) (Info)
Species: acaulis (a-KAW-liss) (Info)



Water Requirements:

Average Water Needs; Water regularly; do not overwater

Sun Exposure:

Sun to Partial Shade




Foliage Color:

Unknown - Tell us


6-12 in. (15-30 cm)


6-9 in. (15-22 cm)


USDA Zone 5a: to -28.8 C (-20 F)

USDA Zone 5b: to -26.1 C (-15 F)

USDA Zone 6a: to -23.3 C (-10 F)

USDA Zone 6b: to -20.5 C (-5 F)

USDA Zone 7a: to -17.7 C (0 F)

USDA Zone 7b: to -14.9 C (5 F)

USDA Zone 8a: to -12.2 C (10 F)

USDA Zone 8b: to -9.4 C (15 F)

Where to Grow:

Unknown - Tell us


Unknown - Tell us

Bloom Color:

Pale Yellow

Bloom Characteristics:

Unknown - Tell us

Bloom Size:

Unknown - Tell us

Bloom Time:

Mid Summer

Late Summer/Early Fall

Blooms repeatedly

Other details:

Unknown - Tell us

Soil pH requirements:

Unknown - Tell us

Patent Information:

Unknown - Tell us

Propagation Methods:

From seed; direct sow outdoors in fall

Seed Collecting:

Allow pods to dry on plant; break open to collect seeds


This plant is said to grow outdoors in the following regions:

Riverside, California

Chicago, Illinois

Patriot, Indiana

Lincoln Park, Michigan

Akron, New York

Buffalo, New York

Penn Yan, New York

Rochester, New York

Watertown, New York

Cleveland, Ohio

Tulsa, Oklahoma

Philadelphia, Pennsylvania

Trafford, Pennsylvania

Austin, Texas

Sterling, Virginia

Lake Mills, Wisconsin

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Gardeners' Notes:


On May 31, 2021, mwb5 from Indian Trail, NC wrote:

Would love to find a source for plants or seeds for this awesome but hart to find plant...anyone?


On Aug 13, 2011, John_Riley from Markham,
Canada wrote:

We are in Markham, Ontario, Canada. We have a few of these plants and only now have discovered it's actual name. Thanks for including nine o'clock in the description.
Our stories would be the same as all the others, including gatherings in our yard at dusk. I have a video of the opening if i am able to upload.


On Aug 13, 2004, rsohps from Murrysville, PA wrote:

Watching these bloom at about 9 pm is like watching time lapse photography. They attract hummingbird moths in the evening. DO NOT mulch. I lost almost all of mine due to mulch. Reliably hardy in Zone 5 near Pittsburgh, since I've had mine for at least 10 years.


On Jul 12, 2004, cdb from Lake Mills, WI wrote:

This plant has been the cause of many evening gatherings in our garden. Bloom time is quite dramatic and we've even been known to cheer as the flowers open! I'll add as a beginning gardener the evening primrose is not difficult to grow.


On Jun 18, 2004, snowtrillium from London,
Canada wrote:

To cllect seed from this plant -
In september/October after blooming is finished, look under the leaves at the base of the plant and gather the seed pods.
Dry and store ,or open the pods and sprinkle where wanted.

To transplant seedlings or mature plants-
overcast/rainy day dig and keep as much soil on the root as possible
It will go into severe shock.
Plant and keep shaded untill shock wears off.


On Jun 5, 2004, ambest from Riverside, CA wrote:

This is my second yr. of the beautiful evening primrose. Here in Ca., it opens up around 5p.m., and mine are in partial shade, so they remain open til around noon. This yr. I will be getting lots of seeds, I recommmend this plant to anyone who enjoys beauty and the smell is outstanding. Mine are planted with pink valerian, lavender, morning glories, sea lavender,and pink sage, also pretty white yarrow. It makes a very beautiful and fragrant garden....enjoy!


On Apr 5, 2004, JenniesWorld from Spencer, WV wrote:

The Evening Primrose, also called Nine-O-Clock in West Virginia, is an intriguing plant. The opening of the flowers at precisely nine p.m. (Daylight Savings Time) is a magical experience. First, the petals begin to tremble, then as the petals begin to seperate the bud is vaselike, but as the petals expand the flower snaps open to reveal a creamy yellow center. The Hummingbird Moths, fairly rare here, thrive on the nectar and they are as fascinating to watch as the flower-bud opening is!
This is the plant from which they extract Evening Primrose Oil, high in bebeficial GLAs.


On Nov 18, 2003, VeganGurl20 from Tulsa, OK wrote:

This plant is easy to grow, attractive, and makes lots of beautiful, sweet smelling flowers. I thoroughly enjoy this plant!