This pink-flowered, leafy-stemmed perennial is native to Europe and Asia and is naturalized throughout sunny, open areas of North America. Long ago, native peoples learned that rubbing this plant’s roots in water would produce foamy suds. This is due to the presence of compounds known as saponins, a term derived from the Latin word for soap.
Soapwort contains 15 to 20 percent saponins by weight. Before soap was invented in the early 1800s, soapwort and other saponin-rich plants were used to cleanse both the body and clothing. At one time, soapwort was also added to beer to create a frothy head. In the Middle Ages, the herb was called Herba fullonis, referring to its use to “full” or clean and thicken woolen cloth.
Common Names: Bouncing Bet, Soapwort
Description: Single, erect, leafy stem, up to 2 feet tall; opposite, lanceolate leaves up to 3 inches across; terminal clusters of five-petaled pink blooms
Hardiness: To Zone 3
Flowering: July to September
Parts Used: Leaves and roots
Range/Habitat: Native to Asia and Europe; naturalized throughout sunny, open areas of North America
The root may have antibacterial and expectorant properties. In folk medicine, it has been taken internally to treat upper respiratory conditions, such as coughs and bronchitis, and applied externally to treat skin problems, such as eczema, psoriasis, acne, and poison ivy. Soapwort and other plants that contain saponins are not widely used in herbal medicine today, however, as these compounds are very irritating to the intestinal tract and can cause nausea, vomiting, and diarrhea.
A familiar wildflower, soapwort is lovely when naturalized along the edge of a woodland garden or hedgerow. The blooms draw butterflies and hummingbirds. The double-flowered variety ‘Rosea Plena’ and others have been bred for garden use.
When mixed with water, the viscous saponin in soapwort forms a lather that can be used to cleanse delicate fabric or skin. Soapwort can cause eye irritation, so be cautious if you use it as a body cleanser.
How to grow it
Soapwort is very easy to grow in average soil and full sun to partial shade. Plant seed outdoors in either spring or fall or, for earlier bloom, start seed indoors under lights in late winter. The plants will self-sow, and propagation is rarely necessary. To prevent soapwort from becoming invasive, cut back the plants immediately after the flowers have faded. Use the cut tops to make natural cleaning products. Dig up roots for the same purpose in fall.