Salvias are a great source of blue or purple in the garden. They prefer full sun or light shade, well-drained soil and twice-a-week watering. Many interesting hybrid varieties are available.
S. dorrii (Purple Sage) 12 in. tall by 24 in. wide; purple flowers in July; native to Nevada
S. x superba May Night (May Night Salvia) 3 ft. tall by 2 ft. wide; dark purple flowers from July-August