Selected cultivar from the type species, Armeria maritima 'Koster' is an old horticultural form, appreciated in rock plant collections and sunny borders for the particular intensity of its floral color. Like the species, it belongs to the Plumbaginaceae family.
It forms a dense and compact tuft of linear, narrow, evergreen leaves, dark green, soft to the touch, forming a regular cushion 10 to 15 cm high excluding flowering. The upright floral stems, reaching 20 to 25 cm, bear globular heads of bright pink to deep pink, significantly more intense than most wild forms of the species, surrounded by their characteristic membranous bract collar of the genus.
In its natural habitat, the type species blooms from April to July. In cultivation, 'Koster' blooms from May to July, with a generous and regular floral production over several weeks.
Like all thifts, it requires full sun and well-drained, rather poor soil, without excess winter moisture. Its resistance to wind and summer drought makes it a strong candidate for exposed rock gardens, walls, and gravel gardens, where the profusion of its colorful stems animates the composition for a long time.