Saponaria × lempergii

Common Name: soapwort 
Type: Herbaceous perennial
Family: Caryophyllaceae
Zone: 3 to 7
Height: 0.75 to 1.50 feet
Spread: 1.00 to 1.50 feet
Bloom Time: August to October
Bloom Description: Light reddish-purple to carmine pink
Sun: Full sun
Water: Dry
Maintenance: Medium
Suggested Use: Ground Cover
Flower: Showy
Tolerate: Deer, Drought, Dry Soil, Shallow-Rocky Soil

Culture

Winter hardy to USDA Zones 3-7 where it is easily grown in moderately fertile, neutral to slightly alkaline, well-drained soils in full sun. This hybrid is generally considered to be less tolerant of high summer heat, humidity and poorly-drained soils than other species in the genus, thus making it a challenging plant to grow well south of USDA Zone 7.

Noteworthy Characteristics

Saponaria is a genus containing annual and perennial pink family herbs that are native to Eurasia, with primary concentrations occurring in the Mediterranean area of southern Europe. Genus plants are commonly called soapwort in reference to the soapy lather-producing qualities of the leaves, stems and roots which contain the glucoside saponin. Genus plants, in particular S. officinalis, have historically been mixed with water to produce a soap used for a variety of purposes including washing clothes or dishes. Showy pink or white flowers bloom in loose upper axillary open clusters, each individual flower having five petals (additional petals in double flowered varieties), a five-toothed calyx, ten stamens, and two or occasionally three styles.

Saponaria x lempergii, commonly known as soapwort, is a procumbent hybrid perennial whose parents are Mediterranean species (S. cypria and S. haussknechtii). This hybrid typically grows to 12” tall spreading to 18” wide on well-branched stems. It features lance-shaped, soft hairy, dark green leaves (each to 1/2” long) and axillary light reddish-purple to carmine-pink flowers (to 1” long) with long reddish-pink calyces. Flowers bloom from mid-summer into fall.

Genus name comes from the Latin word sapo meaning soap.

Hybrid name honors Dr. Fritz Lempberg of Styria, Austria.

Problems

No serious insect or disease problems. Watch for slugs and snails.

Garden Uses

Perhaps best in cottage gardens and wild areas. Interesting small area ground cover. Also effective in borders. Thrives in the well-drained soil conditions of rock gardens and raised beds. The late summer flowers are often greatly appreciated in areas where few flowers in other genera are typically in bloom.