I've been using old CDs; simply put masking tape over the hole and then use either white glue or a glue gun to affix the bushes and rocks. The bushes are aquarium plants and cost about $5.00 a pack. The rocks came from my garden path.
Once the terrain is dry I liberally apply watered down white glue and then cover with hobby sand.
After the sand dries I always put another layer of watered down white glue to help seal the sand in place.
Once the second layer of sand is dry I apply static grass. I decided to this quick and easy so I did not dry brush the sand this time.
28 mm figures on the terrain.