If you catch them watering the dead flowers, pick them up and drop them on the farm instead. You have to keep on top of these guys or they will just waste their time and do unproductive things.

Just make sure your villagers are working the farm and it will bloom sooner or later. Unfortunately, there doesn't seem to be a set amount of time that it takes to bloom, so cross your fingers that you get some crops before everyone starves.

I find that turning off the game for a half hour or an hour helps kick start the farm.