What is the best way to make LOD?

I’ve created some realistic grass, bushes, ferns but when placed in large quantity it hampers game performance so I wanna create some LOD’s for my grasses etc. but I don’t know how because they are low-poly and have particular shape and if i decide to decrease those polygons then shape of my ferns change and in case of grass they are planes combined together. What are the ways yo improve my game performance because even far-cry 4 has high grass count at some places but it doesn’t hamper game performance but mine do.

If your grass is already fully optimized then LOD may no longer be an option, your best chance to improve performance is to adjust Cull distance Min and Max value, that’s if using the foliage tool. For my third person game I use Cull distance (Min 1 max 2000), that means no grass beyond 20 meters of my postion will render.

I Hope that helps.