I can't really figure what is wrong with this particular grass, but it looks nice when you look at it 2x, but at 1x (real size) it looks too bright and blurry. My guess is that you tried to put too much detail on it, and since the colors are quite soft, the lack of contrast blends the details too much at 1x. I'm not to sure on how to improve that one in particular, you can try improving contrast, tweaking the palette or maybe trimming some detail.
~K