to possibly elaborate on the electro-magnet idea, perhaps you can hook the
power up to a a
fader of some sort and slowly decrease
power. You also would vary the amount of metal on each petal. The petal with the least metal would fall first while the petal with the most metal falls last.
also like the glitter idea... I would rim each petal with a dull glitter, just enough to stand out without reflecting so much light that it's obvious that glitter was used. Just an idea, you will definitely have to experiment to get the result you are looking for...
Another idea that just occured to me is, depending on the distance the audience is from the rose, you may want to make the rose a
bit larger-than-life. And if you are creating one from scratch, frequently look at it under the
stage lighting to make sure that it looks the right shade of red or pink or whatever color you choose.