No matter the occasion, whether for St. Patrick's Day or an Incredible Hulk-themed birthday party, dark green icing makes the difference between keeping with the theme and missing the mark. Dark green is a tertiary color derived from combining the primary colors of green and blue. With color mixing in mind, you can achieve the hue of dark green icing needed to top cakes, cookies and cupcakes.
Place 1 cup of white icing in a bowl. Add 40 drops of green food coloring and 6 drops of blue food coloring.
Stir the frosting and food coloring with a spoon to distribute even color. Gage whether the color green is dark enough.
Add and stir in one drop of blue food coloring at a time until the icing reaches the dark green color you desire.