Here is a tutorial of how I did the foliage for my thesis, Protégé.
You can download a pdf of the tutorial here: https://www.artstation.com/artwork/Z4v5N
This is just one of the many ways you can make plants for a scene and I just wanted to share what I have learned from my process. The final environment is rendered real time in Unreal Engine 4. Foliage modeled in Maya and ZBrush and then brought into Substance Designer to finish it off. Feel free to contact me if you have any questions and I hope you enjoy and learn something!