Moss Paint. Here’s how: In your blender, combine: One can of cheap beer or 1 1/2 cups buttermilk ..A few handfuls of moss.. One teaspoon of sugar. Blend until the mixture is smooth, and you’re ready to get painting! You can use a brush to paint your moss onto concrete walls, rocks, or brick. Mist the moss once a day to help it thrive, and soon your green graffiti will take hold!