Best way to light grass?

I am just getting started messing around with different ways to make good looking foliage for nature scenes. My problem is that I can't get the light to hit the grass I've created to match the lighting for the ground under it. The method I've landed on (for performance reasons) is making plane with a transparent mesh on it, and duplicating it for the other side. It works great for the trees, but trying to apply it to grass isn't working out as well. The problem is that the light hits the ground differently than the grass and it makes the place where the grass and ground meet very noticeable. I can fool with the shaders and get one side looking right, but the other side is always too light or too dark.

Heres some pics if it will help (sorry the images are so dark):

^ This is where the grass looks wrong. You can see the definite place where the grass and the ground meet.

^ This one looks right, but I can't seem to make it match consistently.

The issue Im having is that the light hitting the ground doesn't hit the grass in the same way because there is such a difference in the angle of the two. I am wondering if there is way to throw the light on the grass so the whole is lit from the top instead its actual angle, or if theres a way to make it match the ground better. I can't be the only one to have run into this problem, if anyone has any advice I would be very grateful. Basically I want the grass to be almost unnoticeable unless there is something behind that is different, like a stone path or the character or a building. Also, it has to be using a transparent shader.

Thanks.