This is a very pretty garden escape which has become naturalised, mostly in its 'double' form where the stamens have been replaced by extra petals. It is a perennial plant growing to about 70cm tall and bearing soft pink flowers (25-35mm across) which stand clear of the sepals in a crowded head from July to September. The leaves are narrow with 3 conspicuous veins and are opposite. It produces a delicate scent believed to attract moths. This is not a native plant and it belongs to the family Caryophyllaceae.
I first identified this wildflower in 1981 at Castlecove, Co Kerry and I photographed it near Wellingtonbridge, Co Wexford in 2007.
If you are satisfied you have correctly identified this plant, please submit your sighting to the National Biodiversity Data Centre