These clumping evergreen perennials have grassy, straplike foliage that vary in color, width, and height. Native to Australia and New Zealand, Dianella are mostly drought tolerant and generally need some degree of shade. Full sun in foggy coastal areas. 'Cassa Blue' is a compact, non-cane forming cultivar of Dianella caerulea with soft blue leaves up to 18"-24" tall. Dark blue flowers appear above the foliage in spring. Evergreen to 24F and root hardy to at least 10F.