How to change Scale by Grass Density

I am trying to make a 20 km² big island and started experimenting with ways to get grass into the game. Since painting the grass takes way too much space and time (and probably looks bad) i used the “Landscape Grass Type” blueprint with a custom gray scale texture to spawn the grass on demand.

The only problem is than in low density areas you can see the full scale grass meshes spread out over a large distance.

The only way to fix this is by somehow scaling the grass down based on the density of itself or the gray scale image but keeping the density about the same size.

My question now is:

Is there a way to edit the “Landscape Grass Type” blueprint OR scale it down in the materials editor?

I really hope there is some kind of easy solution since i just started using UE4 and don’t mind spelling mistakes since English is not my native language.