Hex #55b51d or rgb(85,181,29) in RGB space is the tint of grass green. It has hue angle of 97.89 degrees, value = 71 and saturation = 84. #55b51d can be obtained by mixing 3 colors: 2 drops of yellow, 1 drop of blue, 3 drops of green.
Nearest safe hex - #66cc33. Below you can see the block with #55b51d color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #55b51d to the mixer and play with it.