Achillea, or commonly called yarrow, is an excellent choice for a butterfly garden. Also attracting hummingbirds, the large clusters of fragrant flowers require full sun and are drought tolerant. Achillea first appear in late spring and flourish through late summer, growing 12 to 36 inches tall and wide. To encourage repeat blooms, trim spent flowers. Various vibrant colors are offered as options. The enchanting blooms are also deer and rabbit resistant.