Culling Terrain detail objects by layer

Hello Everyone,

I've been optimizing my terrain created using the in-built terrain creation system, and I'm currently going through the hell that is terrain.buildpatchmesh() (under terrain.details.render) and in an effort to contain this problem, I'll like to cull some terrain detail (grass and shrubs) to a shorter distance.

will it be possible to do this, and please how do I go about it (changing the layer of the detail prefabs? ).

Thanks.