Companion plants for Geranium (Annual)
Geranium (Annual) blooms from May through October. It wants full sun and moderate water. The 8 companion pairings below each state why the pairing works.
Blooming before Geranium (Annual) opens

Siberian Squill
Shares full sun and moderate water; blooms in early spring, before this one opens; lower at 6 in, for the front of the border; blue against red, for contrast.

Windflower
Takes full sun to part sun and moderate water; blooms in early spring, before this one opens; lower at 6 in, for the front of the border; blue against red, for contrast.
Blooming alongside

Candytuft
Shares full sun and low to moderate water; opens in mid spring and overlaps into this one's season; evergreen, so the bed keeps its shape through winter; lower at 10 in, for the front of the border.

False Indigo
Shares full sun and low to moderate water; its seed heads stand through winter, for structure and the birds; taller at 3.3 ft, for the layer behind it; blue against red, for contrast.

Sneezeweed
Shares full sun and moderate water; its seed heads stand through winter, for structure and the birds; taller at 3.3 ft, for the layer behind it; orange sits close to red on the wheel.

Little Bluestem
Shares full sun and low to moderate water; its seed heads stand through winter, for structure and the birds; taller at 3.3 ft, for the layer behind it; orange sits close to red on the wheel.

Feather Reed Grass
Shares full sun and moderate water; its seed heads stand through winter, for structure and the birds; taller at 4.9 ft, for the layer behind it.

Switchgrass
Shares full sun and low to moderate water; its seed heads stand through winter, for structure and the birds; taller at 4.9 ft, for the layer behind it; pink sits close to red on the wheel.