‘Thundercloud’ is a dome-shaped cultivar that typically grows in a low mound to 12″ tall and 12″ wide. Pointed, gray-green leaves retain good color throughout the growing season. Tiny, star-shaped, white flowers with a pink blush cover the foliage mound with bloom in mid to late summer. Flowers are attractive to butterflies. Spent flower clusters typically retain shape and add some winter interest to garden areas. Plants are drought tolerant once established.