Creating Dark Green

During the summer of 2008, I took a painting class at the local community college. At the same time, I was studying the works of John Singer Sargent and noticed that he often used a very dark green background for his pieces such as "Lily, Lily, Rose". I did a bunch of paintings with this dark green background ("Study on Sargent's Poppies" is on the right.)

I am beginning a new painting, "Ketones 1" that will be done similarly to "Study on Sargent's Poppies" but I could not remember exactly what I did to create the dark green. I googled and found a recommendation to add black to the green. I practically never use black, so I was sure this was not what I did. After some thought, I remembered mid-tone green and mid-tone red make charcoal grey. So, if I add a little more green than red, would I have dark green?

It worked! And created a very rich wonderful dark green - much darker in value than each of the two original colors in fact. I will have to experiment with complimentary colors more!