How would you make grass blow in the wind?
I did a tutorial on this using one bone and some weight painting:
Hope this helps!
Could you make another tutorial how to make wind blow tree leaves and branches on trees?
Trees are a bit more complicated as moving the leaves would expose the branches of the tree, you might need to use a python script for trees or you could try using another bone and weight painting around the outside of the leaves/tree. Additionally you could use an armature for the tree but i’m not sure how well this would work on a larger scale.