Saponaria ocymoides. Height to 10-40cm (4-16"). Rock Soapwort is a favourite perennial for alpine and rock gardens. This semi-evergreen blooms from May to August with five-petaled pink flowers joined at the base to form a nectar tube that is highly attractive to bees. Provide good drainage. Try planting spring flowering bulbs beneath it so that their flowers and foliage rise above. The roots really can be used to make soap. Rock Soapwort looks marvelous in containers, but best in situations when it can trail and seed itself. Plant it in rock trough gardens to to grow on a rock wall.
This perennial produces excellent, summer-long blooms on low growing plants that work well in containers and rock gardens. Continue reading below for some tips on how to grow Saponaria from seed.
Season & Zone
Exposure: Full sun to partial shade
Hardiness: Saponaria is hardy to Zone 3
Start indoors in peat or coir pots 8-10 weeks before planting out. Alternately, direct sow in early spring or early autumn. For best results, place the seeds on the surface of pre-moistened soil, and tuck inside a plastic bag. Refrigerate for three weeks, and then provide bright light and a soil temperature of 21°C (70°F). Germination should occur in 10-21 days.
Transplant into dry, rocky soil in full sun or partial shade at 10-20cm (4-8”) apart. Water only during very dry spells, and do not fertilize. Cut back after blooming to keep plants compact. Saponaria plants do not transplant well, and they dislike wet soil over winter.