This is a herbaceous perennial that grows quite well in Sydney gardens. It originated in Europe and belongs to the Caryophyllaceae family. It has soft basal leaves and in mid to late spring it sends up spires of delightful notched-edged, clear pink blooms (ht 60 cm). It enjoys sun and well-drained, reasonably moist soil. The clumps may be periodically divided to increase the plants. It can be seen growing wild along the sides of the roads in England, where it is known as red campion or ragged robin. To me is a quintessential English cottage garden plant. Its rounded flowers provide a good contrast to the spires of Salvia, which begin their long blooming period in late spring. It also can look good with wallflowers, Dianthus and Orlaya.
I gave up on this plant for a while as mine disappeared, possibly because it was crowded out by other plants or grown in too heavy a soil. A friend encouraged me to try again, and I placed my new plant at the edge of a raised bed in full sun and didn't let other plants encroach upon its space. I was pleasantly surprised at how well it did. I hope it will keep going, and I intend to divide it regularly so that it doesn't get too congested.