Companion plants for Primrose
Primrose blooms from March through May. It wants part shade and moderate water. The 8 companion pairings below each state why the pairing works.
Taking over as Primrose finishes

Rhododendron
Shares part shade and moderate water; overlaps, then carries the display into early summer; stands well above at 6 ft, a canopy to plant beneath; evergreen, so the bed keeps its shape through winter.

Meadow Rue
Shares part shade and moderate water; blooms in early summer as this one finishes; taller at 4 ft, for the layer behind it; both offer pollinator forage, in different months.

Beautyberry
Takes part sun to part shade and moderate water; blooms in early summer as this one finishes; stands well above at 5 ft, a canopy to plant beneath; both offer pollinator forage, in different months.

Goatsbeard
Shares part shade and moderate water; blooms in early summer as this one finishes; taller at 4 ft, for the layer behind it; both offer pollinator forage, in different months.

Northern Sea Oats
Shares part shade and moderate water; blooms in midsummer, extending the bed's season; taller at 3.5 ft, for the layer behind it; its seed heads stand through winter, for structure and the birds.

Foxglove
Shares part shade and moderate water; overlaps, then carries the display into midsummer; taller at 4 ft, for the layer behind it; both offer pollinator forage.

Summersweet
Shares part shade and moderate to high water; blooms in midsummer, extending the bed's season; stands well above at 6 ft, a canopy to plant beneath; both offer pollinator forage, in different months.

Wishbone Flower
Shares part shade and moderate water; blooms in early summer as this one finishes; both offer pollinator forage, in different months; purple against yellow, for contrast.