Percedual Foliage question + Kite demo question

Hello everyone!

I am finally taking time to learn how to use this system in 4.9.2 and I have a question involving the Kite Demo assets.

Using the Landscape material from the Kite demo auto layers the terrain + adds grass. I found the grass type and used it to begin adding trees and rocks. I finally have it perfect but there’s no collision. Is this not the correct way to use it? I like this method because I can control placement by painting with the erase foliage layer in the landscape paint section.