After using the sculpting tool to create the tree in Blender I rendered the image with the Cycles preference. Although the asset at this point is far from optimized for proper use, I wanted to explore the idea visually.
I then brought the image into Photoshop where I used my knowledge of color theory to hand paint a daytime and night-time version of the tree using just a few layers and blending modes to achieve the illusion of bark.
As a traditional painter, I enjoy each of my digitally painted pieces to have a touch of that painterly brush stroke which can be observed in the way I handled the edges and highlights of the piece.