Golden yarrow and blue catmint add interest at the top of the wall.
yarrow is an excellent alternative to traditional turf.
While western yarrow has a low palatability rating, it is eaten by domestic and wild grazers early in the season.
British Dictionary definitions for yarrow
any of several plants of the genus Achillea, esp A. millefolium, of Eurasia, having finely dissected leaves and flat clusters of white flower heads: family Asteraceae (composites) Also called milfoil See also sneezewort
Old English gearwe; related to Old High German garwa, Dutch gerwe