Hey @Livat1984,
There are currently four commercial third party solutions for your task (that I am aware of):
Forrester is a full blown plugin suite for vegetation generation. Taio is also a vegetation solution which integrates nicely into the Insydium toolkit. Laubwerk is more an asset library with an optional surface distribution plugin. Poliigon also offers bindings for its asset library to Cinema 4D, including a vegetation library. With Cinema's own Mograph (Cloner, Fields, and MoSpline) system, Scene Nodes, and our asset library you can also get pretty far.91d029d5-d9b0-49c9-9528-0cd69b35c60e-image.png
Fig. I: Cinema's own asset library comes with substantial content in the Plants section (all the content does not even fit on my screen, there is more). Finally, a while ago a user posted here a free plant generator, but I am not sure if it is being maintained.
Cheers,
Ferdinand