It’s such a pretty plant, petite and delicate, only a few inches high and covered with quarter-inch flowers of the softest pink. It’s the kind of groundcover perfectly suited for small spaces, rock gardens, and fairy bowers. It can even be used as a lawn substitute, as it tolerates limited foot traffic. With so much to recommend it, I’ve often wondered why this hardy perennial isn’t more popular. Perhaps it just needs a better name. “Soapwort” fails in the marketing department!
More officially known as Saponaria ocymoides, soapwort is native to southwestern Europe, but is surprisingly well-adapted to Colorado’s more extreme climate. Gardeners have reported success growing it in USDA zones 2 through 10! It’s described as semi-evergreen, although at 7,100 feet I found it a bit less than “semi-,” especially after harsher winters. Still, the roots are eager to start growing again when the weather warms, and late spring brings an abundance of blooms.
Saponaria isn’t fussy about soil, handling sand and clay with aplomb. It prefers full sun, tolerates part shade, and does best on the dry side. Soapwort isn’t invasive, but it will gently reseed and naturalize if you let it. Shear off the dying flowers if you don’t want more seedlings, and to keep a tidy appearance. It’s also a good idea to trim off any winter-killed foliage in the spring when growth resumes. Otherwise, little maintenance is needed.
The flowers are attractive to honeybees, another European species. Happily, deer and rabbits tend to avoid the foliage. Perhaps that’s because consuming too much causes nausea, vomiting, and diarrhea, due to the presence of the toxic substance saponin.
So why do we call this lovely beauty “soapwort”? “Wort” just refers to a small plant traditionally used as food or medicine. And how is soapwort used? One guess.
Yes, plants in this genus have been historically used as soap, a practice that is again growing in popularity. Boiling the roots in water results in fat-dissolving suds, perfect for laundering delicate fabrics. Straining off the liquid that is left after boiling the leaves in water yields a soap substitute for dry skin. You can even buy soapwort shampoo and body wash.
The Saponaria typically grown for this purpose is a different species: Saponaria officinalis. However, this is one soapwort I do not want to grow in my garden. Also known as Bouncing Bet, it grows three feet tall, and spreads aggressively by both seeds and rhizomes. Besides, growing it here in Colorado is illegal, as it’s on the state noxious weed list.