Oenothera

( ee - noh - THEER - uh )

At-A-Glance Information

Oenothera, commonly called Evening Primrose or Sundrops, is a genus of annual, perennial and biennial flowering plants that that are prized for their blooms in shades of yellow, pink and white. Evening Primrose can survive harsh conditions and neglect, and is considered easy to grow. Flowers are typically white, yellow, pink or red-orange, and can be fragrant. Plant Sundrops in containers, in the outskirts of gardens for quick color, in mixed beds, or to spill over walls and steps. They do well as groundcover, in rock gardens, or native, pollinator, informal, and cottage landscapes.

Oenothera Species and Varietals

Oenothera is a genus of about 145 species and is a member of the plant family Onagraceae. Plants in this genus are closely related to those in Fuchsia, Clarkia (Mountain Garland), Chamaenerion (Willowherb, Fireweed). The former genus Gaura has been subsumed into Oenothera. The best growing zones for Evening Primrose are USDA hardiness zones 4-9, though this varies somewhat depending on the species cultivated. For more information, see the descriptions below. To find your zone, click here: Zone Map.

Oenothera albicaulis (Prairie Evening Primrose, White-Stem Evening Primrose, Whitish Evening Primrose, Whitest Evening Primrose)
These annual plants are native to North America and produce beautiful white flowers with protruding white stamens. Individual plants produce stems that reach up to 1 foot long, and spread horizontally in a circle out from the root. Flowers open at sunset and remain open for several days before fading. Best in USDA hardiness zones 5-9.

Oenothera berlandieri (Berlandier's Sundrops, Evening Primrose, Mexican Evening Primrose, Pink Ladies, White Evening Primrose)
This species is native to south-central United States and northern Mexico, where it grows on dry prairies and rocky or sandy areas. It forms a semi-woody perennial subshrub that produces showy yellow flowers in summertime. Individual plants reach up to between 9 inches and 2 feet tall with a spread of about a foot. This species is considered weedy in the garden due to its fast-spreading underground rhizomes and vigorous seeding. Cultivars include 'Siskyou' (with pink flowers) and 'Twilight' (with plum-purple new foliage that matures to green-bronze with purple variegation and pale pink blooms).

Oenothera biennis (Common Evening Primrose, Evening Star, Sundrop, Weedy Evening Primrose, German Rampion, Hog Weed, King's Cure-All, Fever Plant)
Used to create Evening Primrose Oil, these plants are native to eastern and central North America. Individual biennial plants reach over 5 feet tall in their second year of growth. Flowers bloom from late spring through late summer, and are yellow. Common Evening Primrose is suited for USDA hardiness zones 3-9. It is considered invasive in Europe, Asia, Africa, and Australia.

Oenothera caespitosa (Tufted Fragrant, White Evening Primrose, Desert Evening Primrose, Fragrant Evening Primrose)
This species of Evening Primrose is either a perennial or biennial and grows well in USDA hardiness zones 4-9 or Sunset growing zones 1-3, 7-14 and 18-21. It is native to western regions of the United States and reaches 8-12 inches tall and 2 feet wide at maturity. Foliage is grey-green and fuzzy and flowers are fragrant and fade from white to pink, opening in the evening. Flowers bloom profusely in late spring and early summertime.

Oenothera californica (California Evening Primrose)
These plants are native to southwestern to northern California and Baja California, Mexico. These perennials produce a spreading upright stem that reaches up to 31 inches long, and flowers occur in upper leaf axils. They are typically white and fade to pink with age. This species grows well in USDA hardiness zones 7a-10b.

Oenothera curtiflora (Gaura parviflora) (Velvetweed, Velvety Gaura, Downy Gaura, Smallflower Gaura)
This species is native to the United States and Mexico, and produces a 6.5 foot tall annual herbaceous plant. Flower spikes rise to be about a foot taller than the foliage and are covered in greenish-pink flower buds. Blooms open at night or just before dawn and are pink. This species grows well in USDA hardiness zones 3-9. This species is known internationally as an agricultural and environmental weed, and is considered invasive in Australia, China, Japan, and South America.

Oenothera deltoides (Birdcage Evening Primrose, Basket Evening Primrose, Lion in a Cage, Devil's Lantern, Dune Primrose, Antioch Dunes Evening Primrose)
These plants are native to the southwestern United States and northern areas in Mexico. They grow in sandy or coastal habitats. Plants are greyish-green and produce white flowers with yellow centers. Individual plants reach up to between 2 and 12 inches tall and have a spread of around 3 feet. It grows well in USDA hardiness zones 8a-11a.

Oenothera fruticosa (Sundrops, Narrow-Leaved Sundrops, Narrowleaf Evening Primrose)
This species grows best in USDA hardiness zones 4-9 or Sunset growing zones 1-21 and is native to the eastern United States. It has an erect growing habit and grows to 2 feet tall and wide with reddish stems. Yellow flowers bloom from late spring through summertime, and open in daytime. Varieties include 'Fireworks' (with red flower buds and leaves that are tinted red), Oenothera fruticosa glauca (also called Oenothera fruticosa tetragona; with light yellow flowers and red stems), and 'Solstice' (with bright red summer foliage that darkens to burgundy in fall).

Oenothera gaura (Gaura biennis) (Biennial Gaura, Biennial Beeblossom)
These plants produce light pink flowers that age to vibrant reddish-pink in summertime. Flowers are very attractive to pollinators. These plants are native to North America, and reach about 6 feet tall when in bloom (foliage reaches about 3 feet tall). Biennial Gaura grows well in USDA hardiness zones 5-9. It is considered invasive in California and the northeastern United States as well as regions of Australia.

Oenothera hartwegii (Hartweg's Sundrops, Western Primrose, Fendler's Sundrops)
This species is native to the deserts in the southwestern United States and northwestern Mexico. These perennials typically reach between 12 and 18 inches tall when mature and in bloom and 24 inches wide. Green foliage is very thin. These plants can form a fantastic drought-tolerant groundcover that produces yellow flowers in summertime. Best in USDA hardiness zones 5-9.

Oenothera lindheimeri (Lindheimer's Beeblossom, White Gaura, Pink Gaura, Lindheimer's Clockweed, Indian Feather)
These plants are native to an area that stretches from Louisiana through Texas, and forms a plant that reaches between 20 and 60 inches tall when mature and in bloom. Flower spikes rise above foliage, supporting delicate white to pink flowers with long stamens. Flowers bloom from the beginning of springtime through the first frost of the cooler months. This species is suited for growing in USDA hardiness zones 5-9. Cultivars are listed and described below:

'Ballerina Blush'
Soft, shell-pink flowers on a 1-2 foot tall plant.

'Belleza' Series
Compact, tidy plants for smaller spaces. To 12-18 in. tall and 12-20 in. wide.

'Rosy Jane'
Bicolored pink and white flowers on a 1-2 foot tall plant.

'Siskiyou Pink'
To 3-4 feet tall with deep pink to magenta flowers.

'Stratosphere' Series
Profuse flowers on an upright plant.

'Whirling Butterflies'
Popular choice for gardens, with pure white flowers atop red-green 2-3 foot stems.

Oenothera macrocarpa (Bigfruit Evening Primrose, Ozark Sundrops, Missouri Evening Primrose, Missouri Primrose, Glade-Lily, Wingfruit Evening-Primrose)
These plants are native to southcentral United States and northern Mexico. They produce red stems up to 18 inches tall that hold large flowers up to 5 inches across. Blooms are typically canary yellow with a mild fragrance. Cultivars include 'Greencourt Lemon' (with pale green-yellow flowers and wavy grey-green leaves and red stems), 'Comanche Campfire' (with blue-grey foliage and small pale yellow blooms), 'Lemon Silver' (to 6-8 inches tall with silver-green leaves and bright yellow blossoms), and 'Silver Blade' (with bright yellow flowers and narrow silver green foliage).

Oenothera nuttallii (Nuttal's Evening Primrose, White-Stemmed Evening Primrose)
Native to western Canada and the north-central United States, these wildflowers reach about 2 feet tall when mature and in bloom and are typically found in grasslands, sagebrush landscapes, and plains. This species prefers sandy soils to perform well.

Oenothera odorata (Evening Primrose, Fragrant Evening Primrose)
Native to South America, these plants reach between 24 and 36 inches tall when mature and in bloom. They produce summertime flowers that open yellow and turn red with age. Cultivars include 'Apricot Delight' (with light orange-peach flowers), 'Sulphurea' (with gold-yellow blooms), and 'Lemon Sunset. This species grows well in USDA hardiness zones 4-10.

Oenothera pallida (Pale Evening Primrose, White Buttercup, Pale Primrose)
These plants are native to British Colombia, the western United States and northern Mexico. They produce white flowers that fade to pink with age. Plants typically reach about 2 feet tall and have green to blue-green foliage. Cultivar 'Innocence' is valued for its large white flowers that age to light pink; to 10 inches tall and 3 feet wide. This species is suited for growing in USDA hardiness zones 3-9.

Oenothera rosea (Rosy Evening Primrose, Rose Evening Primrose, Pink Evening Primrose, Rose of Mexico)
These plants are native to the Americas, but have naturalized in many other areas of the world. Blooms are less than an inch in diameter and vary in color from pink to red. Individual plants reach up to 2 to 3 feet tall when mature and in bloom with a spread of 12 to 18 inches. Foliage and stems are green. Rosy Evening Primrose is considered invasive in the southern United States and Northern California, Japan, New Zealand, Australia and South Africa.

Oenothera serrulata (Yellow Sundrops, Halfshrub Sundrop, Serrate-Leaved Evening Primrose, Shrubby Evening Primrose, Plains Yellow Primrose, Halfleaf Sundrop)
These plants, native to central North America, form a bushy clump of foliage to 18 inches tall. Foliage is green, and flowers are white, fading to pink or orange as they age. Bloom time for this species is between March and November. They are both heat and drought-tolerant, and can grow in many types of substrate. Yellow Sundrops grows well in USDA hardiness zones 3-9.

Oenothera speciosa (Pinkladies, Pink Evening Primrose, Showy Evening Primrose, Mexican Primrose, Buttercups, Amapola)
These herbaceous perennial wildflowers have smooth stems and are native to grasslands in Kansas, Missouri, Nebraska, New Mexico, Oklahoma, and Texas. Flowers bloom from March to July, and are shell-pink. Individual plants reach up to 12 to 24 inches tall and 18 to 24 inches wide at maturity. Foliage is true green.

Oenothera suffulta (Roadside Gaura, Honeysuckle Gaura, Kisses, Bee-Blossom, Wild Honeysuckle)
These flowers are endemic to an area that ranges from Texas through Oklahoma and are annuals. They reach about 4 feet tall and form a basal rosette of green leaves. Foliage is smooth, wavy or tooth-edged, and lower leaf surfaces are hairy. Flowers are present from April through June, borne on tall spikes that rise above foliage. Blossoms are white. Best in USDA zones 7-9.

Oenothera suffrutescens (Scarlet Beeblossom, Scarlet Gaura)
These plants form perennial herbaceous subshrubs with woody bases and heavy roots. Stems range in length from 4 inches to over three feet long. Flowers are typically white to yellow in color, and fade to orange or pink with age. Flowers are strongly scented. Use these plants in wildflower gardens, or in outer edges of the landscape where spreading, deep rhizomes will not interfere with other plantings. Scarlet Beeblossom grows well in USDA hardiness zones 5-9. This species is considered invasive in California.

Oenothera versicolor (Red Evening Primrose, Sundrops, Red Sundrops, Orange Evening Primrose, Suncups)
These plants are native to South America, and are popularly cultivated as garden ornamentals in many areas of the world. They are suited for USDA hardiness zones 5-10. These bushy perennials reach just over three feet tall, and produce flowers on spikes that rise above foliage. Blooms are reddish-orange, and a open during the day. Cultivar 'Sunset Boulevard' produces blooms that transition from apricot red to deep red-orange as they age and reaches to 12-14 inches tall and wide.

Caring for Oenothera

Oeonothera, or Evening Primrose, plants are typically grown from seed, but can also be purchased as seedlings or starts from a reputable nursery (they are generally available in summer or fall). Plant these flowers in a space in the landscape that receives full sun to partial shade. They thrive in a spot that gets between 6 and 8 hours of sun each day, but can handle some afternoon shade, especially in warmer climates. They can grow in a wide variety of soils, as long as they are well-draining, nutrient-rich with added organic material, and have a slightly acidic to neutral pH. If local soils are particularly poor in nutrients or do not drain well, make sure to amend the planting area with plenty of organic compost before installing. Water newly planted Evening Primrose regularly to help it develop a strong root system. At maturity, these plants are drought-tolerant, able to get by on rainwater alone with some supplemental waterings in the warmest months of the year.

Fertilize yearly in early springtime with an application of 2 inches of compost around the base of plants. Pull mulch back before applying, work the compost gently into the soil a bit, water it in, and then replace mulch. These plants are not heavy feeders, and this should be sufficient to provide the necessary nutrients for the active growing and flowering seasons. Pruning these plants is simple: remove spent blooms (which will lessen reseeding) and any unsightly foliage. They bounce back well from pruning, especially in the spring and summer months. Late in the season, they can have a tendency to get leggy, especially when grown in too much shade. Plants can be cut down to about four inches tall at this point, and a flush of new growth and flowering will be triggered.

Propagation

Oenothera, or Evening Primrose, plants are best and most easily propagated through harvesting and sowing seeds. These plants will readily re-seed and tend to spread into areas of the garden where they may not be wanted. Volunteer seedlings can be dug up while they are still young and replanted elsewhere, or seeds can be intentionally sown in mixed beds or borders. To propagate your Evening Primrose plant, follow the instructions below:

Propagating Oenothera by Seed

Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. The best potting medium for seed germination is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
Harvest your seeds. The seed heads on plants are pretty easy to spot, they're left behind after flowers have faded. Once they have dried out and begun to split open, you can harvest the seeds inside. Cut them off of the plant, placing them in a paper bag. Harvest as many as you can, and place the paper bag in a dry, cool, dark area. They will continue to split open and release the seeds contained inside. Once they have been released, take them out of the bag and put them in a container so you can work with them.
In either late winter or early springtime, get your container prepared. Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. Germination usually takes between 5 and 30 days from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 65 and 72 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.

Oenothera seeds are held inside of the dried seed pods left behind after flowers fade.

Oenothera seeds are very tiny and typically dark brown to brown in color.

Problems and Pests

Certain species of Oenothera are considered invasive in some regions; see the species descriptions above for more information. Check with local authorities before planting. Oenothera, or Sundrops, can be susceptible to developing issues with the following pests and diseases in the landscape: