Over the hill

This is the first render of my first scene in blender. If anyone knows how to get the grass shorter i would appreciate knowing.
I used weight painting to create a vertex group then added that to the hair particle system. i think thats the best way to create grass. the grass isnt textured. the color comes from the orange light in the cave which affects the whole scene for some reason.

the grass looks fine in the front. Wild grass grows just like that. scale the grass in the back and reduce the color if you can. Near the water in the back looks like short grass. Looks like a scene out my back door.