With kitchen scissors, cut off the white portion at the stem end of each rose petal. With a mortar and pestle or in a food processor, mash or process into a paste, gradually adding 1/4 cup sugar.
In a large saucepan, bring water to a boil. Stir in remaining sugar until dissolved. Stir in the rose paste. Boil, without stirring, for 10 minutes. Remove from the heat; cool for at least 1 hour.
Strain, reserving rose syrup. Discard rose pulp. Squeeze the juice from the oranges and strain; discard pulp and seeds. Add 2-2/3 cups orange juice and food coloring if desired to the rose syrup. Transfer to a freezer container; cover and freeze for at least 8 hours or until firm.
Verify that flowers are edible and have not been treated with chemicals.