The blade-like texture of grass and weeds is one of the most difficult effects to re-create on a diorama or model railroad.
But a little felt will produce grass that appears to grow out of the soil.
You can buy felt at a fabric store in 9-by-12-inch squares or by the yard in 6-foot widths. Use dark green, or buy beige felt and paint it with green ink (from an art supply store). The beige felt can also be used to simulate dried grass for winter scenes.
Use scissors to cut the felt to fit your project. Use plaster, papier-mâché or insulation board (like Styrofoam) to create the shapes for the hills you will cover with grass. Apply a thick coat of water-based contact cement and press the felt into the still-wet cement. Let it dry. Wash your hands and the brush.
Now the fun part: Get dirty! Sift some real soil through a door screen to remove debris and larger stones, then pour it through a fine-mesh tea strainer. Shake the strainer to distribute the soil onto the felt. Try to cover about three-fourths of the felt.
Use a wire bristle brush such as a pet brush to stroke the felt so loose strands fluff up.
Sift on more soil as needed. You want the individual fibers of teased-up felt protruding through the soil, just like real grass. Trim excess with scissors.
When you’re satisfied with the scene, spray the area with a mixture of five parts water to one part Artist’s Matte Medium (available at art supply stores). Add a drop of detergent to the mixture to help soften the fluid so it doesn’t puddle as easily.
You’ll need to spray on enough of the mixture so the entire area has a white cast. It will turn the soil and felt a darker shade. Let it dry for about a week, and the original colors will return.