Saponaria ocymoides, commonly referred to as rock soapwort, is a semi-perennial herbaceous perennial plant native to the rocky slopes of the mountains of south-central and southwest Europe.
There are 30 to 40 species in the Saponaria genus. With its abundant flowers and vigorous growth, this perennial plant has made its home in gardens everywhere. These plants were not only cultivated for their conspicuous flowers but were also cultivated for practical reasons such as soap.
This plant is also known as Common Soapwort, Wild Sweet William, and Crow Soap.
Rock Soapwort is densely branched with a creeping habit, creating a 6 to 8″ high mat with a 1 to 2” spread. The leaves are ovate to lanceolate, up to 1 inch long and 0.5 inches wide, gray-green in color, and held close to the stems.
The leaves and stems are covered with fine hairs. The plant is lined with sprays of bright pink flowers 0.5 to 1″ in diameter from May to August. The flowering period can take up to three weeks. Rock Soapwort will self-seed in the garden itself but is not viewed as aggressive.