Companion plants for Yarrow
Yarrow blooms from June through September. It wants full sun and low water. The 8 companion pairings below each state why the pairing works.
Blooming before Yarrow opens

Candytuft
Shares full sun and low water; blooms in mid spring, before this one opens; both are strong pollinator plants, and they feed in different months; evergreen, so the bed keeps its shape through winter.

Texas Mountain Laurel
Shares full sun and low water; blooms in early spring, before this one opens; both are strong pollinator plants, and they feed in different months; evergreen, so the bed keeps its shape through winter.

Rock Cress
Shares full sun and low water; blooms in mid spring, before this one opens; both offer pollinator forage, in different months; evergreen, so the bed keeps its shape through winter.

Blue Princess Holly
Shares full sun and low to moderate water; blooms in mid spring, before this one opens; both are strong pollinator plants, and they feed in different months; evergreen, so the bed keeps its shape through winter.

Howard McMinn Manzanita
Shares full sun and low water; blooms in late winter, before this one opens; both are strong pollinator plants, and they feed in different months; evergreen, so the bed keeps its shape through winter.

Rosemary
Shares full sun and low water; blooms in early spring, before this one opens; both are strong pollinator plants, and they feed in different months; evergreen, so the bed keeps its shape through winter; they only overlap in zones 8 to 9.
Blooming alongside

False Indigo
Shares full sun and low water; opens in late spring and overlaps into this one's season; both are strong pollinator plants; its seed heads stand through winter, for structure and the birds.

Prairie Junegrass
Shares full sun and low water; opens in late spring and overlaps into this one's season; both are strong pollinator plants; evergreen, so the bed keeps its shape through winter.