Ok so its late... like 2:30 am bare with me if I make any mistakes or am unclear!

Step 1: Make your Image, and decide what color you want your base for your grass to be... you can remember this color or make a duplicate of the layer before you get to step 2.

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Step 2: Grunge up the layer, make sure you toss a couple complementary in there, and don't worry to much about it at all actually, just get some information with close colors down.

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Step 3: Gaussian or how ever you spell it blur. do it till you can hardly make out the prior shapes.

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Step 4: Smart Sharpen the blurred layer, I like to use amount 100% radius 1 px which I believe is default. Also im not 100% on the math, but i think the radius is how far this filter goes per run, so on a 1024 wide map, I am going to have to repeat this process 1023 times which is not hard because all I need to do is use the shortcut to repeat command (ctrl+f on windows and cmd apple u? on mac {not sure about that}). Just be aware, because if you are making a large map like i tend to do (12000 px) then this may... will require a macro.

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Step 5: Repeat step for eleven bagillion times... till you end up with this:
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Be calm, it will take a couple times to notice anything.

Step 6: Make base Layer with your starting color, if you did not duplicate off start, put it under the new design. Now set the top layers Opacity down somewhere below 50 depending on the effect you are going for, and set to multiply or color burn... other will work too.

Finished Result Time to complete (depends on the size) 1024 x 800 was only 3 min, or so and that is with me taking screens to write this:

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