Here's what I do. I set up a plant stage in Vue. Death Valley makes a good one. I delete the ground plane. I then generate whatever plant I want on two or three levels and rows....ie 3 rows of 4. Disable shadows or move them so no plant's shadow falls on another. I then arrange the lighting. Usually I do one render with light from the left, one from the right and one from above. Make sure that the ambience and shadows are set correctly. Then I render and save the color image and alpha image. Then I make Paint Shop Pro tubes out of them. I then go back to my Vue image and spray plants and trees wherever I want them and as many as I want. If done patiently and correctly, you cannot tell the difference between the sprayed tree and an actual mesh in the scene. Of course, you have to know how to use layers and color adjustments, painted shadows and other keys of postwork. I use this technique often in work for architects and landscaping clients. It save me billions in polygon weight and render times. Just another option. Monsoon