Water is your best bet.

Yes, if you run sprinklers continuously through the night and into the next morning.

The trick is that water releases heat when it freezes. So if you keep the blossoms wet, that freezing process keeps them right at 32°F—cold enough to damage nothing. But you have to start before the frost hits and keep the sprinklers running until the ice melts naturally. Stopping early is how you kill the buds.

Covers work too, but only if they go all the way to the ground to trap heat. Fabric or frost cloth, not plastic—plastic just gives them a cold greenhouse effect.

Don’t bother with tarps or trash bags. They’ll do more harm than good.