Moss graffiti is the eco-warrior’s answer to traditional chemical laced spray paint! Click the arrows to see Show Me How‘s illustrated, easy to use guide to making your own living, breathing work of art. Not only is Moss graffiti perfect for environmental messaging, it is also a fun form of guerrilla gardening.
Source: Paint Moss Graffiti – Step-by-Step Guides for Offbeat DIY Projects – Popular Mechanics
www.wikihow.com/Make-Moss-Graffiti has an alternative recipe that uses buttermilk/yogurt, water/beer and sugar and corn syrup to get a thick paint like consistency. They also advise to check back weekly to either spray the design with water (to encourage moss growth, especially if you live in a dry environment) or apply more moss-paint.