I'm lazy... Especially when it comes to little design details like moss. But luckily UE4 has some great tools for this. Just wanted to share the easiest solution i found. This can be used with blended normal maps as well :)
It can be expanded with many techniques such as using 'world aligned textures' on top of the 'world aligned blending' so even meshes with the same rotations have different texture patterns. Hope it is useful!
Stay creative!