The paperclay was painted and aged with pastels and washes, and bits of green "moss" were glued between the bricks. The moss is used by model railroaders in their layouts.
The dirt is dried, used coffee grounds. The white "oyster shells" are crushed eggshells. My family got awfully tired of eating eggs while I worked on this part of the project. Under the house, where it wouldn't be seen easily, I daubed white paint. The fencing is made from pieces of contractor's foam with purchased plastic "wrought iron" fencing.
This is an overhead view of the base with some of the plants and a couple of trees. With the foam base, it was easy to poke the greenery into the ground. I pulled it back out, dipped it in glue, and pushed it back in. You can see the bare spots where the brick pillars from the house go. I decided not to glue the house in place to facilitate moving it.