Just a note on blue from a watercolorist and fellow blue lover:
Try planting blue's compliment color, orange/peach next to it to bring out the blue to the eye rather than yellow, which is the compliment to purple.
As a fellow gardener, I have too been on a permanent search for true blue flowers.
Blue Plumbago, blue Amsonia and Blue Mist Spirea are blues with no red to their coloring. This is a great thread and thanks to all!
