Is sprite healthy for plants

yes it does. flower preservatives supplied with cut flowers contain sugar, an acidifier and gemicide. Sprite has sugar which flowers use to feed on and citric acid which works as an acidifier. you can also try to use 7up or a drink like that, but don't get the sugarless or diet ones! you can also try to use table sugar and lemon juice, but don't overdose them, two tablespoons of each is enough =)