not shore if this is something I need to do in Blender or UE4, I am using a program called Tree[D] and importing the models to blender then to UE4, but when I import them I cant seem to get the dabble sided geometry to work, event when it is check in the model editor in UE4, and I have tried to find a solution in blender but I cant seem to find any info on it. any help would be good. the Tree[D] program seems very good and it’s free. I can crate high and low poly trees in minutes and manipulate and Texture them in anther program. but not being able to see the 2 sides of the faces is annoying me to no end and making the Tree/Bush look very thin
Do you mean the trunk or the leaves?
leaves -> enable “two sided in the material”
trunk -> add a “solidify” modifier 
that worked.
thanks’ 10