True. Really. If you want no flowers and possibly a dead plant, baby that baby. Otherwise ignore it and it will thrive. Strange but true. I need more like that. ;-)

If they're already established, you can probably cut back on the watering. However, if the plant is doing well under current watering practices, suddenly cutting off its steady supply of irrigation may stress the plant severely.

It depends on the root structure, if they have been there a long time and have nice, deep roots you can do with very little water. If it is on a weekly drip you will need to cut the watering back in stages so you don't kill them. Eventually you can eliminate them from the drip system and just give them a good soak once a month in the summer. They need very little in the winter time, if at all.

I have a ten year old bougainvillea at a rental house I own that I shut off the water to in april. So this bougainvillea went from April through October in the full sun of a Phoenix summer with not a drop of water. Did it bother it? Heck no, I had to cut half of it down because it had grown so much. Once established they need nothing.