Hex #558b39 or rgb(85,139,57) in RGB space is the tint of grass green. It has hue angle of 99.51 degrees, value = 55 and saturation = 59. #558b39 can be obtained by mixing 4 colors: 5 drops of yellow, 5 drops of blue, 3 drops of green, 2 drops of black.
Nearest safe hex - #669933. Below you can see the block with #558b39 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #558b39 to the mixer and play with it.