Commelina
These bright blue bulbs are summer flowering, and are in the garden by the glass-house. I've never known much about them, so I've checked with Wikipedia. Looks like my Commelinas, or Asiatic dayflowers, are Commelina communis, the best known species in the West.
commelina in flower
Allow me to quote from Wikipedia : 'It is a common weed in parts of Europe and throughout eastern North America.' Oh well. It's such a pretty blue, and I haven't noticed too many problems. Yet!