What are the complimentary color of green?

Since brown is considered a neutral, there is no true compliment. Brown is made by mixing red, orange, or yellow pigment with either black or their respective complimentary colors. Therefore, taking into account the original base colors, and their respective compliments (red w/green, orange w/blue, yellow w/violet) we see that the common shade in the compliments are blue. Therefore, the practical (though not precise) compliment of brown would be blue.