Background step-by-step (Patreon)

I start by laying down a rough sketch with the perspective and general setting.

Then I use a soft large brush to color the basis of the background. The trees are drawn on a seperate layer.

Using a textured cloud brush, I add more color detail to the ground. The moss on the trees are made using a foliage brush.

More detail added using grass brushes while color picking from the ground colors. The detail on the rocks are drawn by using a rougher brush. 

Final details added using various grass brushes and flowers. The tree and leaves in the foreground are blurred out to add depth to the perspective.