|Showy, clump-forming perennial with a brilliant floral display. Leaves are narrow and toothed, to 5 inches long. From summer to fall, fragrant, 1 inch blooms appear in huge clusters on tall stems above the foliage. Many named varieties are available in a wide range of colors. Great in borders, rock gardens, formal beds and meadows. Mildew may be a problem towards end of season. Divide, using outer plants every 2 to 3 years. 'Amethyst' bears violet flowers.