Three types of grass painting techniques. Grass one - fan brush
sap green and white
sap green
sap green and cadmium yellow
Add a little detail if you wish with a size 0 or script liner brush
Grass two - silhouette
raw umber
use size 0 round brush or script liner for fine detail
Grass three - close up
Sap green, cadmium yellow and a little white
I'm using a size 2 and size 0 round brush