For taller grass I use jute twine, the type of stuff you might tie up old newspapers with.
I take a long piece of it. From one end, about an inch up, put a drop or two of crazy glue, and wind it tight. When it's dry, cut the twine right through the crazy glue. Then hold the glued end and unwind all of the little fibers to straighten them out. Eventually, you'll figure out a little assembly line procedure to speed up the process, but that's, in essence, what I do. I can easily do hundreds of these on a day when I don't feel like modeling....like when watching a football game, etc. Then I have a bunch of tufts of grass when I need them. Best of all, if you want dry grass, you don't even have to paint the stuff. But if you want green, I "plant" the tufts into some styrofoam, airbrush them, and then put them into whatver base I'm using later. My bases are almost always pink polystryene foam, so it's easy to plant the grass into the bases.
Hope this helps.
Rob