Just dry it out slowly and carefully upside down. No hairspray or soda or anything! As long as it drys slowly, and you're careful with it afterwards, it'll last ages!

SPRITE omg put it in Sprite (The soda) it wont die I promise :) or but the stem off and put the top in the freeze it will last forever <3

you have to hang it upside down in a dark place! (and after a time spray hairspray on it) I have a rose that's like that for already 3 years!

White rose! < 3