Hello everybody. This is my very first forum post 
. I made a custom tree but when I try to place it in the terrain editor, the tree shows up as being half under the terrain and half over it. All of the other trees work fine. Is there a way to offset the y for the tree?
Welcome to the forum.
Make sure that while saving your tree in your 3d package, it’s pivot’s Y axis is 0/just touching the ground.
also, build a few roots or trunk below the y-axis pivot… or when you place your trees on hills, the base will be floating off the floor