No, if you want to go that direction, you should render out a diffuse texture as targa with a green background that matches the the grass color, then render out a frame where the grass is white and the background is black, then add it to the alpha channel in photoshop.
I make my alpha first, get that looking awesome then doing texturing so I dont have to redo the texture/alpha if its not looking right. Very easy to slap some 10second green/brown colors for the difuse when testing out the alpha. I also do this with trees.