thanks for the first feedback. i wanted to buy something off cornucopia but found that i need to login with my office account ... so that has to wait until i get my data from the office :) then i bought the terrapak (was on my radar for some time, now i had the excuse to actually do it ... waiting for the download link though). so in the meantime i am trying to figure out how grass is defined.

i placed one single patch of grass and had a look at the material settings.

then i fired up the gimp and created a blue to yellow gradient as color map which resulted in this.

i chose the extreme colors just to easily see where they go ...

and then finally i tried to change the shape of the grass blades and found its controlled by the transparency map (again created something with gimp leading to this).

so with this i can start finetuning color and shape of a single patch of grass ...

will keep you updated on my endavour in growing vue grass :)