Commelina tuberosa

BLUE, so blue, its a must have for blue lovers. Easy too. 

Little ones cheap until they grow up. 

Mexico. Intense blue three petalled flowers fall from green hoods. An autumn treasure. 90cm. Sun or part shade.   Hardy yet exotic looking.  I have it in my sand bed in full sun and it is charming. Evidently it can romp away, perhaps in tropical climates, not here. The flowers open in the morning only, and while to can be a bit lax and not so pretty at the bottom, plant it behind another low plant.