Peter Cottontail™ Yarrow

Peter Cottontail™ is an Achillea ptarmica cultivar developed by Hans A. Hansen for Walters Gardens. Its dense, rounded mound of green foliage carries large ivory-white flowerheads on upright branching stems, with an early-summer display lasting nearly seven weeks in Michigan trials. ## Distinguishing traits The [U.S. plant patent](https://patents.justia.com/patent/PP31756) records the cultivar denomination 'Peter Cottontail', its 2014 seedling cross, and stable propagation by cuttings. It describes a rounded mound about 20 inches tall and 3 feet wide on average in a Michigan trial, with plants reaching roughly 21 inches tall and 3⅓ feet wide. The [Walters Gardens profile](https://www.waltersgardens.com/variety.php?ID=ACHPC) lists 18–24 inches in height and 28–30 inches in spread, white flowers, and green foliage. The patent was granted as PP31756 on May 12, 2020. ## Garden use Use it as a specimen, in mass plantings, borders, containers, rock gardens, or as a cut or dried flower. Walters Gardens lists bees and butterflies among visitors and reports resistance to deer and rabbits. The [RHS profile](https://www.rhs.org.uk/plants/381640/achillea-ptarmica-peter-cottontail/details) describes white button-like flowers in summer and autumn and classifies the foliage as deciduous. ## Growing conditions Grow in full sun or partial shade and provide good drainage. The RHS recommends moist but well-drained soil. The patent says established plants tolerate dry summer conditions but perform best with ample moisture and good drainage; USDA hardiness zones 3–8 are listed by Walters Gardens. ## Maintenance Regular pruning is not required. Remove faded flowers if you want to prolong the display; RHS recommends spring division for propagation. Water new plants as they establish, then adjust supplemental watering to local rainfall and soil conditions.