During the summer months everything is so green. It often makes painting landscapes difficult because of the lack of variations with the color. When needing more variations with greens, it's often tempting to buy more green tube colors and use them get different hues. Most of the time adding more greens to the palette doesn't work very well. I find it best to keep my palette simple and mix most of my greens with blues and yellows often adding a touch of red to the mix. Adding more colors to the palette will more often than not simply make the painting less harmonious.
I usually start with a wash of of burnt sienna on the board, let it dry and then work my greens over that. It lets some warmth come through and dampens the harshness of the greens. Remember that all the greens in a scene like this will reflect and influence just about everything else like the rocks. A touch of green in all these other elements will give the painting unity.