Wetting flash paper is probably not the best idea, because it slows down the burn rate of it. Now here is my thought onto how to accomplish a rose transformation.
You have the thing floating in front of you and a rose in a flip stick position your free hand goes to grip the floating paper, your other hand flips the rose out as you palm and break your hook revealing a rose. You could also if you wanted to add a flash to it use Fism Flash John Cornelius.
Now another way you could go about this is using a sort of bubble zombie technique (Losander) you use a cloth and a rose like a zombie (omnomnom Brains). Somehow maneuver the floating mass out of site, a topit maybe of good use. Basically you are doing a small version of the Asrah but a piece of paper to a rose.
Hope these help
