Blue is tough. I remember when I first moved here, I wanted to build a pond. I was also attracted to a lot of Monet's paintings in which he used the color blue. At the time the best blues I could find were in irises like "Chivalry". Delphiniums are a good blue and you have the benefit of "pressing" them - they retain the blue color the best in my opinion. True Blue Gentian, Veronica Royal Candles and Rozanne geranium are pretty good too. For shrubs and trees, I like Taube hydrangrea and Blue Atlas Cedar.
