Blooming from late spring to mid-summer, Achillea tomentosa 'King Edward' (Yarrow) creates a colorful carpet of yellow flowers above woolly grey-green foliage. (Achillea tomentosa is also known by the common name Woolly Yarrow.) It spreads to make a perfect groundcover, works well in a small space, and is a great choice for a rock garden. Butterflies love this perennial and deer and rabbits avoid it. Native to Eurasia, it thrives in low-fertility soil and a full-sun location. It also tolerates some foot traffic, making it an easy care solution for natural areas where walkers tread.