Companion plants for Giant Allium
Giant Allium blooms from May through June. It wants full sun and low water. The 8 companion pairings below each state why the pairing works.
Taking over as Giant Allium finishes

Globe Thistle
Shares full sun and low water; blooms in midsummer 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.

Blazing Star
Shares full sun and low water; blooms in midsummer 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.

Black-Eyed Susan
Shares full sun and low water; blooms in midsummer 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.

Lavender
Shares full sun and low water; overlaps, then carries the display into late summer; both are strong pollinator plants; evergreen, so the bed keeps its shape through winter.

Sunflower
Shares full sun and low to moderate water; blooms in midsummer 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.

Switchgrass
Shares full sun and low water; blooms in late summer, extending the bed's season; both are strong pollinator plants, and they feed in different months; its seed heads stand through winter, for structure and the birds.

Passionflower
Shares full sun and low to moderate water; blooms in midsummer as this one finishes; both are strong pollinator plants, and they feed in different months; climbs to 13 ft behind it, height without the footprint.
Blooming alongside

Grape Hyacinth
Shares full sun and low water; blooms in early spring, before this one opens; both offer pollinator forage, in different months; lower at 8 in, for the front of the border.