Pink Evening Primrose
Oenothera speciosa by Jacqueline Palmer

Click on Image for Close Up of Flower
Photo by Curtis Swift

SCIENTIFIC NAME: Oenothera speciosa

USDA HARDINESS ZONES: 5- 8 (hardy to -20 degrees F)

TYPE: herbaceous perennial

FAMILY: Onagraceae

HEIGHT: 12" to 24"

Introduction:

Pink (also Mexican or Showy) Evening Primrose is a tough, adaptable ground cover that spreads quickly. Few plants give as much color for so long with so little care. Flowers 1 1/2 in. wide are carried on stems 10-12 in. high. They open daily from spring through summer, and contrary to their name, they open in the daytime. Basically pest free and drought tolerant, Oenothera speciosa, sometimes referred to as O. Rosea, loves sun.

Culture:

O. speciosa thrives on little or no care once established. Spreading on stoliniferous rootstocks (rhizomes or runners) and by seed, it can become invasive if not controlled. Pink Evening Primrose makes a good ground cover for dry slopes, rock gardens, or parking strips and grows best with full sun in well-drained alkaline soil. O. specious is not as fragrant as its cousin O. Missourensis, or Missouri Primrose, but it's just as eye-catching.

Propagation:

Seed and division

Problems:

If grown in moist, fertile soil O. speciosa can take over. Stems die back after bloom, which can lead to stem rot. Infrequently white fly invasion can be a problem (in wetter climates). Over watering can lead to powdery mildew. Some people think it has an untidy look, even though the color show can be dramatic.

Related Species:

O. speciosa's most well-known relative is the sunny yellow Missouri Primrose, O. missourensis, . Some texts list the names Oenothera berlandieri, or O. speciosa childsii as synonyms, or alternative botanical names, for O. speciosa. Other texts use these two names to describe a white flowering form. Another selection called "Siskiyou" exists that is lighter pink, more compact, and more nearly everblooming than O. speciosa.

Text References:
  • Brenzel, Kathleen N., Ed. 1995. Sunset Western Garden Book. Sunset Publishing, Menlo Park, CA.
  • Hyde, Barbara, 1993. Gardening in the Mountain West, Vol. I. Barbara J. Hyde, Inc., Longmont, CO.
  • Hudak, Joseph, 1993. Gardening with Perennials Month by Month, 2nd Ed., Revised and Expanded. Timber Press, Portland, OR.
  • Roth, Susan, 1997. Better Homes and Gardens New Complete Guide to Gardening. Meredith Corporation, DesMoines, Iowa.
  • Tenenbaum, Frances, Ed., 1994. Taylor's Master Guide to Gardening. Houghton Mifflin, New York, NY.

Web Sites of Interest:

Plant List & The Gardens at the Mesa County Extension Office Colorado State University

home gif The `Gardens at the Mesa County Extension Office'

to the Tri River Area Gardening and Horticulture Home Page

Curtis Swift, Area Extension Agent (Horticulture)
November 21, 1999