Maybe sand/pva brushed on then painted then flocked?
That's a popular technique, but these days I prefer to texture with filler (spackle). You just paint it on, and making sure its not too wet, and nice and tacky, you stipple with an old brush. Doesn't look like much when wet, but when dried it comes out as a fantastic fine texture. Much easier than playing with sand. Then paint and drybrush up... Or paint and give it a dark wash.
Here's a vid of The Terrain Tutor texturing with this method...
Also, when flocking, you can make much more interesting 'grass' than just using one flock / static grass. Try mixing several together into a unique blend. Or do patches of a darker one first, then when thats dry, do a lighter one over all - the first one will add some nice visible dark patches.