Plants that bloom in September in Zone 11 with blue flowers

Borage

Star-shaped electric blue flowers that bees go absolutely wild for. Self-sows freely.

Lisianthus

Rose-like ruffled blooms with the vase life of a chrysanthemum. The flower farmer's secret weapon for high-end arrangements.

Plumbago

Sky-blue phlox-like clusters bloom nonstop in warm climates. The blue flower that thrives where most blues melt in summer heat.

Statice

Stiff papery flower clusters that dry to keep their color for years. A cut-flower farmer staple for wreaths and dried bouquets.