Companion plants for Lady's Mantle
Lady's Mantle blooms from May through July. It wants part shade and moderate water. The 8 companion pairings below each state why the pairing works.
Blooming before Lady's Mantle opens

Tall Oregon Grape
Shares part shade and moderate 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.

Coloratus Wintercreeper
Shares part shade and 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.

Serviceberry
Takes part sun to part shade and moderate water; blooms in mid spring, before this one opens; both are strong pollinator plants, and they feed in different months; its white flowers settle the green.
Taking over as Lady's Mantle finishes

Zigzag Goldenrod
Shares part shade and moderate water; blooms in late summer as this one finishes; both are strong pollinator plants, and they feed in different months; its seed heads stand through winter, for structure and the birds; this one spreads, so it will crowd its neighbor in time.

Northern Sea Oats
Shares part shade and moderate water; overlaps, then carries the display into early fall; both are strong pollinator plants; its seed heads stand through winter, for structure and the birds; this one spreads, so it will crowd its neighbor in time.
Blooming alongside

Pinxterbloom Azalea
Shares part shade and moderate water; opens in mid spring and overlaps into this one's season; both are strong pollinator plants; evergreen, so the bed keeps its shape through winter.

Feathered Friends Fancy Finch Ajuga
Shares part shade and moderate water; opens in mid spring and overlaps into this one's season; both are strong pollinator plants; evergreen, so the bed keeps its shape through winter.

Periwinkle
Shares part shade and low to moderate water; opens in mid spring and overlaps into this one's season; both are strong pollinator plants; evergreen, so the bed keeps its shape through winter.