Companion plants for Annual Phlox
Annual Phlox blooms from May through September. It wants full sun and moderate water. The 8 companion pairings below each state why the pairing works.
Taking over as Annual Phlox finishes

Swamp Sunflower
Shares full sun and moderate water; blooms in mid fall 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.

Aster
Shares full sun and moderate water; overlaps, then carries the display into mid fall; both are strong pollinator plants; its seed heads stand through winter, for structure and the birds.

Fireworks Goldenrod
Shares full sun and moderate water; overlaps, then carries the display into mid fall; both are strong pollinator plants; its seed heads stand through winter, for structure and the birds.

Pink Muhly Grass
Shares full sun and low to moderate water; overlaps, then carries the display into late fall; both are strong pollinator plants; its seed heads stand through winter, for structure and the birds.

Switchgrass
Shares full sun and low to moderate water; overlaps, then carries the display into mid fall; both are strong pollinator plants; its seed heads stand through winter, for structure and the birds.
Blooming alongside

Chinese Fringe Flower
Takes full sun to part sun 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.

Castle Rouge Blue Holly
Shares full sun 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.

Indian Hawthorn
Shares full sun 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.