Hex #558a40 or rgb(85,138,64) in RGB space is the tint of grass green. It has hue angle of 102.97 degrees, value = 54 and saturation = 54. #558a40 can be obtained by mixing 3 colors: 4 drops of yellow, 3 drops of cyan, 5 drops of black.
Nearest safe hex - #669933. Below you can see the block with #558a40 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #558a40 to the mixer and play with it.