I'm probably not going to be very helpful, but from what I know, if you choose a beautiful town, you don't have to water flowers. Anyway, I'm not too sure on the flower question, although I believe you can "steal" flowers from the island minigames, which should have a broad variety of flowers. In addition, if you have a beautiful town, villagers will be planting flowers often. Very often. Any town I've seen with a beautiful law is completely littered with flowers.
Namine Ritsu <3
But even though those important dreams didn't come true, I'm doing fine.
I wish it was available in previous games! What would happen is I would slack on my flowers one day, and promise to time travel and do two days of watering the next day, and before you know it I had a week of flowers to water.
Now... Ladies and gentlemen...
Get ready for the greatest magic show you'll ever see!