Hartweg Evening Primrose

Calylophus hartwegii subsp. fendleri
Category Ground Cover
Size 2" x 12"
Flower Color Yellow
Flower Season Spring, Early Summer
Exposure Full Sun
Growth Rate
Hardiness 20°F


This fast-growing, bushy, perennial with linear, green foliage and showy flowers grows one foot high and two inches wide. During the spring and early summer, it develops small, yellow, buttercup-like blossoms. The flowers are present for only one day, but the plant continues to produce new blooms; the blooms open at night and start to fade by the next day. It grows best in well-draining soil and is hardy to twenty degrees Fahrenheit or lower. The calylophus may die back during the winter, but re-sprouts quickly it early spring. During winter months, the foliage may turn dull in color or fall from the plant.  It is native to the hillsides, valleys, roadways, plains, and open woods in Wyoming, Nebraska, Arizona, Texas, and Mexico.


This groundcover is drought-resistant and needs only weekly irrigation during the warm weather. Be careful not to over-water this plant. When needed, remove old flowers and growth to prolong the blooming period. Prune it back in the fall to reshape. It likes full sun and reflected heat. The calylophus can also be grown in partial shade but will not bloom as prolifically. Use it in raised beds, as an understory plant in filtered shade, with other perennials in rock gardens for early spring color, or with other drought-resistant plants.
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*Our plant guide provides informational resources regarding plants that we commonly use. HORTICULTURE UNLIMITED IS NOT A NURSERY OR SUPPLIER. We obtain necessary materials for installation purposes only, and recommend consulting a nursery or supplier for direct purchasing needs.
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