Introduce evergreen shrubs and miniature evergreen trees to your yard. Plant them in the ground or keep them in pots, using enough to create a sense of density. Use a variety of tree and shrub types to mimic the diversity of a lush and plentiful forest.
Add a small pond. For a miniature forest, build a small, above-ground pond. Create a circle of stacked rocks. Line the ground and inner walls with weed-blocking fabric followed by plastic pond liner. Secure and hide the top edges of the fabric and liner with one more course of rocks. Fill the pond with water and add a variety of pond plants. Pre-manufactured ponds are also available. A water feature will help convey the sense of a trickling forest stream.
Bring in more small, boulder-like rocks to place here and there throughout your miniature forest.
Plant wildflowers in any spots of sun. Use perennial wildflowers so they will come back each growing season. Plant shade-loving plants in shady areas.
Establish moss in the shady areas. Lay clumps of moss on the soil and around rocks. Keep the moss thoroughly dampened for four to five weeks until the roots become established.
Invite regional fauna to your forest. Keep the pond water healthy so various non-harmful reptiles and insects will feel at home. Hang bird feeders to attract birds. Add a fence or shrubs around the perimeter of the yard if it is not currently secured so small wild animals will feel safe there.