This old world perennial, with its profusion of blooms and vigorous growth habit, has made a home in gardens everywhere. Along with being grown for their showy flowers, these plants were commonly grown for more practical reasons: as soap. Though it is less in use as a cleaning agent now, it still has a special place in many herb and cottage gardens.
Soapwort is prized for its long-lasting blooms. Available in many shades of pink and white, these little flowers are reminiscent of phlox blossoms and bloom freely for months and months, usually starting in late spring, with some varieties carrying on well into the fall months. The flowers have a lovely sweet fragrance, especially in the cooler evening hours. Low-growing types look good spilling over walls in rock gardens, troughs, and containers. Taller varieties work well mixed with other tough perennials, and are seldom bothered by deer or rabbits because of their bitter taste.
About Soapwort Sap
Soapwort first became popular as an ingredient in a gentle soap solution. All parts of the soapwort plant contain high levels of saponins; these compounds can be used to make a mild detergent that's easily dissolved in water and good for cleaning delicate items like lace or sensitive skin. Saponins are poisonous to fish, so avoid planting near ponds and water gardens.
Soapwort Care Must-Knows
Soapworts are easy plants to grow and can be potentially invasive. They can thrive in rocky, sandy soils but for best results, plant in lean, well-drained soils. If the soil is too rich, the plant can become overly lush and floppy, taking on a messy look. Lean soil also helps reduce unwanted spreading.
Plant soapworts in full sun to encourage more compact growth and maximize blooming. When the show is over, shear the plants back for a tidier look and to minimize reseeding. If you are worried about them becoming invasive, grow soapworts in a container, or look for varieties that are a bit tamer.
Related: Container Garden Design Basics
More Varieties of Soapwort
Saponaria officinalis comes in single and double forms slightly larger than a dime, in white, red, or rosy pink. The flowers are held in loose clusters on sturdy 2-foot stems with knots at the nodes. Some forms have variegated foliage. Zones 3-9
Soapwort Companion Plants
Easy and undemanding, veronicas catch the eye in sunny gardens over many months. Some have mats with loose clusters of saucer-shaped flowers, while others group their star or tubular flowers into erect tight spikes. A few veronicas bring elusive blue to the garden, but more often the flowers are purplish or violet blue, rosy pink, or white. Provide full sun and average well-drained soil. Regular deadheading extends bloom time.
The inflated buds of balloon flowers are fun to pop. And they make great cut flowers. Cut them in the bud stage, and sear the base of the stems to prevent the milky sap from seeping out and fouling the water. Most commonly available in blue-violet, balloon flowers also come in pink and white, as well as shorter forms that are better suited for rock gardens and containers. In fall, the foliage of balloon flower turns clear gold, so don't cut the plant down too early so you can enjoy the show. They tolerate light shade, but not wet feet or drought.
Valued for its unusual flower shape, blazing star sends up erect spires of usually magenta, sometimes white flowers. Emerging from grasslike foliage, the blooms make a dramatic statement in flower gardens with other perennials, annuals, or even shrubs. Well-drained but moisture-retentive soil is a must for this prairie native.
Long-blooming helenium lights up the late-season garden with showy daisy flowers in brilliant yellows, browns, and mahogany, centered with prominent yellow or brown discs. Many of the best cultivars are hybrids. All are excellent for cutting. Deadhead to extend bloom time, and divide the clumps every couple of years to ensure vigor.