To my knowledge, there are no cannas with blue foliage or flowers! Cannas may have green, bronze (red) or a combination to the two but not blue. Occasionally someone will describe a canna leaf as being blue-green or even a bronze leaf with pigmentation interspersed with green as being a blue hue but in reality this does not hold up to a color spectrometers criteria for blue.
To date, blue has not been reveled in cannas. I think we are only hoping and wishing.
Regards,
Kent

so....how about the most Glaucous foliage?

Botany: Covered with a grayish, bluish, or whitish waxy coating or bloom that is easily rubbed off: glaucous leaves

canna2grow: are you saying that Botany is the name of a hybrid, or was that just for the definition?

Canna glauca
Canna Erebus
Canna Panache

all have nice bluegreen leaves

Canna Intrigue and deep purple blue leaves

Boca Joe

Thanks Joe; will do!