Hex #558e39 or rgb(85,142,57) in RGB space is the tint of grass green. It has hue angle of 100.24 degrees, value = 56 and saturation = 60. #558e39 can be obtained by mixing 4 colors: 1 drop of yellow, 1 drop of magenta, 1 drop of blue, 3 drops of green.
Nearest safe hex - #669933. Below you can see the block with #558e39 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #558e39 to the mixer and play with it.