All I did was made the grass darker and change the width and length to match the size of my model.
With Mental Ray sun and sky, the grass was really light so I just kept making the grass darker and darker till I got a shade I liked and that worked with my scene.
My model is in inches so I made the grass 4 units long, 0.23 base width, and 0.11 tip width. But I'm going to change it to about 2 inches long which means I'll need to adjust the width too. Oh, I used 1,750,000 density.
One thing I realized is that the size of the blades of grass is crucial. At first my grass was too big so it made the house look really small. The smaller the grass, the bigger the house looks. So, the grass size is crucial to realism.
One more IMPORTANT thing, before I added fur (grass), I applied a grass texture to the plane. Without a grass texture on the plane it won't look right.
Don't be satisfied with what you can do but rather strive to do the things you can't do!