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

Primrose
Takes part sun to part shade and moderate to high water; blooms in early spring, before this one opens; low at 8 in, to carpet the ground beneath; both offer pollinator forage, in different months.

Hyacinth
Takes full sun to part sun and moderate to high water; blooms in early spring, before this one opens; lower at 10 in, for the front of the border; both offer pollinator forage, in different months.

Flowering Crabapple
Takes full sun to part sun and moderate to high water; blooms in mid spring, before this one opens; both offer pollinator forage, in different months; taller at 20 ft, for the layer behind it.
Taking over as Bigleaf Hydrangea finishes

Aster
Takes full sun to part sun and moderate to high water; overlaps, then carries the display into mid fall; its seed heads stand through winter, for structure and the birds; both offer pollinator forage.

Autumn Crocus
Takes full sun to part sun and moderate to high water; overlaps, then carries the display into mid fall; low at 6 in, to carpet the ground beneath; purple sits close to blue on the wheel.
Blooming alongside

Bugleweed
Takes part sun to part shade and moderate to high water; opens in mid spring and overlaps into this one's season; low at 6 in, to carpet the ground beneath; evergreen, so the bed keeps its shape through winter.

Pansy
Shares part sun and moderate to high water; opens in early spring and overlaps into this one's season; low at 8 in, to carpet the ground beneath; purple sits close to blue on the wheel.

Sweet Alyssum
Takes full sun to part sun and moderate to high water; low at 5 in, to carpet the ground beneath; both offer pollinator forage; its white flowers settle the blue.