Here are 4 simple steps to how I drew grass like in my picture Dandelion Seeds. For this tutorial, you will need a program like Photoshop, with smudge tool, dodge and burn. I also use a Wacom tablet (Intuous2, size A5).
1. Draw a chaotic texture in the colors you want your grass to be. I’ve drawn the following texture with the help of a splotchy brush, on which I have enabled scattering. I have used a dark green as a foreground color and a light green/yellowish shade as a background color, and burned some of the places even more to get an uneven coloring.
2. Now, get the smudge tool and set the pressure to 100 percent. Start dragging the colors upwards in grassy, bent straws. Start at the top of the picture and move down, so you will cover the beginning of your previous straws with other straws.
3. Now it’s getting someplace, but looks a bit rough. Take out the dodge-tool and set it on “midtone” range with an exposure that does the trick for you. I use 66 %, but then I have a pressure sensitive tablet, so it won’t be as much as 66% exposure when I draw.
Make a dodge on a bending in the straws of your choice (preferably so it looks like it comes from the same light source), and carefully lighten both up and down from that dodge in the straws. It will be a strong highlight in the middle of the bend, and a softer one as we move away from it.
4. It is starting to look like grass! Now we’re just going to make it a bit more chaotic, so take your burn and dodge tools and draw some straws (like in step 2) with just those. To get a little color into the picture, use the dodge tool with “highlights” as range. Return to step 3 to make some additional lights on these new straws. As a last thing on this step, slightly blur some parts of the grass, so it doesn’t get that sharp feeling. Don’t over-do this, or you will loose all the hard work that you’ve done. And… you know what? Now you’ve got yourself some grass!