Best grown in lean, dry to medium, well-drained sandy loams in full sun. Plants do well in average garden soils and tolerate poor soils as long as drainage is good. Plants also tolerate hot, humid summers and drought. If grown ornamentally, plants are best sited in locations protected from strong winds. Plant stems tend to flop, particularly in hot, humid climates such as St. Louis and/or if grown in moist, rich soils. Consider cutting back plant stems in late spring before flowering to reduce overall plant height. Cutting plants back to lateral flower buds after initial flowering will tidy the planting and encourage additional bloom. Plants may also be cut back to basal foliage after bloom. Divide clumps as needed (every 2-3 years) to maintain vitality of the planting. Plants spread aggressively by rhizomes and self-seeding, and can naturalize into substantial colonies if left unchecked.
Common yarrow is a rhizomatous, spreading, upright to mat-forming perennial that is considered by many to be an aggressive weed. Common yarrow from Europe and Asia was originally introduced to America in colonial times, and has since naturalized throughout the U. S. primarily along roadsides, fields, waste areas and lawns. These species plants are noted for producing deeply-dissected, fern-like, aromatic, medium green foliage and tiny, long-lasting, white flowers that appear in dense, flattened, compound corymbs (to 2-4” across) throughout the summer on stems typically rising 2-3’ tall. Foliage has a strong, somewhat spicy aroma that persists when used in dried arrangements. Species plants are uncommonly sold in commerce, however. It is the cultivars and hybrids of common yarrow, most of which have stronger stems, more upright habits and larger flowers, that have become popular flowering plants for ornamental gardens. Cultivars also extend the range of flower colors to include pinks, reds, creams, yellows and bicolor pastels. Millefolium means thousand-leaved in reference to the foliage. Achillea is in reference to Achilles, hero of the Trojan Wars in Greek mythology, who used the plant medicinally to stop bleeding and to heal the wounds of his soldiers. Common yarrow has a large number of additional common names, including milfoil, thousandleaf, soldier’s woundwort, bloodwort, nose bleed, devil’s nettle, sanguinary, old-man’s-pepper and stenchgrass. Achillea millefolium var. lanulosa (white flowers) is a native American yarrow that, in Missouri, is primarily found growing in unglaciated prairie regions (see Steyermark) of the state.
Stem rot, powdery mildew and rust are occasional disease problems. Plant stems are weak and lodge easily. If grown ornamentally, plants can develop into a tangled mass of stems and foliage by mid to late summer if not cut back. Strong summer rain storms with high winds can easily flatten exposed plantings. May spread somewhat aggressively.
Cottage gardens, wild gardens, meadows, prairies and naturalized areas. This species is generally considered to be too weedy for borders. Can be used as a flowering ground cover or lawn for sunny out-of-the-way areas (mow as needed with rotary mower on high setting).