Hi there
I face a similar problem with my minis. I have used all the typical standby products, including some kind of dried leafy ferm that you buy in big packages in the dried flower aisle at Micheals.
My approach has been to add them together to make the things I want. I have the typical short static grass (never have really mastered that, it just looks like curls of grasslaying flat in the glue. Where is the stand up when you blow on them part coming into this?)
Im including a pic of my Reaper 72MM Anubis using Woodland Scenics tall grass, the dried fern-ish leafy stuff I got at michaels, Static grass, fine sand and wire painted olive green with tan autoflocking added at the end for cattail reeds. If nothing else works youll wind up cutting very fine strips of paper and dying it green either with green watercolor paint or a marker. This often works in larger scales.
HTH
David
Build to please yourself, and don't worry about what others think!
TI 4019 Jolly Roger Squadron, 501st Legion