Champaign-Urbana Herb Society
Herb of the Month
Soapwort is a common perennial plant from the carnation family. Other names include bouncing bet, crow soap, wild sweet william and soapweed. There are twenty species of soapworts altogether.
The scientific name Saponaria is derived from the Latin sapo, meaning soap. From this same Latin word is derived the name of the toxic substance saponin contained in the roots when the plant is flowering. This is why you should not plant soapwort near a pond. The runners of the plant that grow into the water would release the toxic substance and may kill fish. For the same reason, one would not use the plant internally.
The natural range of soapwort extends throughout Europe to western Siberia. It grows in cool places at low or moderate elevations, in zones 3-9.
The plant has leafy, branched stems often tinged in red. It grows 18 inches up to three feet. The leaves are opposite and between 1½ to 4 inches. Each of the five petal flowers has two small scales in the throat of the corolla. The flowers are arranged in dense terminal clusters on the main stem and branches. The individual flowers open in the evening and stay open for about three days. In the garden, the flowers produce a strong scent at night somewhat like sweet fruit with a hint of cloves. It is used to make a raspberry sorbet that captures the scent. However, if the flowers are dried, much of the scent evaporates and is therefore not useful in potpourris.
The toxic elements of the roots are used in the commercial preparation of tahini halva and in brewing to create a beer with a good head. In India it is used as a “galactagogue” which means to increase lactation.
To use the plant as a soap, put the leaves in a pot and cover with rain or distilled water. Boil this for 30 minutes and then strain out the plant matter. You’re left with a soapy water that is still used across Europe in museums and the Catholic Church to wash delicate garments. In this country it was used as a soap for the same reason until Woolite hit the market. You can use the same water to wash your hair. It is also good to use as a soap if you have sensitive skin.
Bouquets of the flower will perfume a room but, again, will lose the scent when dried. The root may be used as a wash for acne and psoriasis when decocted.
It is a lovely and interesting plant for an herb garden that allows one to expand the curiosity of plants to a new gardener.