Korm, short grass was painted sawdust.
Pick a color of latex house paint, thin with water(about half), then stur in sifted sawdust 'till it gets thick(about like bread dough).
Spread this out on a sheet of poly and let it dry. Force the dried clumps through a veg. strainer and it’s ready to use. ALWAYS apply a blend of shades. I used 3.
Tall grass was made from strands of hemp cord; the kind that once was used to bale hay(the old square bales). Somewhere, I ran across a lifetime supply that had been dyed green(you can dye it with RIT clothing dye). Apply a glob of white glue to a piece of scrap wood, snip off a sprig of string, dip the end in glue, then plant the sucker and don’t mess with it. Let it form it’s own pattern.
To give the tall grass a softer texture, I added(after the glue was dry) a VERY thin whisp of poly fiber(used to stuff pillows) accross the top of a grass patch. Applied this thin, the white color dosen’t show much, so don’t worry about that. Most places, I sprinkeled on just a pinch of YELLOW sawdust for weed blooms glued down with a short hit of spray glue. I tried white for blooms but yellow worked much better.
BTW, I found the best way to paint poly fiber is to apply a little latex paint to a tuff and then kneed it "till it’s all colored. You can apply it while the paint is wet or after it’s dry. You’ll still be able to pull off fibers to use.