Make some simple moss bombs to throw at buildings and add some living green to your urban cement-scape.

Step 1: Find Your Moss

Moss can be found in all sorts of corners. I found mine near an abandoned pool. You can also find it online, though expensive, at mossacres.com

Step 2: Gather Ingredients

You'll need:

6 cans of beer. (3 for your bombs, 3 for yourself)
1 box of sugar. (1/2 table spoon per can of beer)
bag of rubber balloons (heavy duty kind will prevent an explosion on your face)
moss (that you collected
acrylic paint (optional)

also:
1 blender
mixing pot
targets
empty soap bottle (to inject solution into balloons) or basting sirynge
empty plastic bottle (or funnel)

Step 3: Grind Moss

Add the moss slowly into a coffee grinder, or blender if you have one. Grind it slowly, because there will be some small rocks that may damage the blender blade or your eye.

Step 4: Mix Ingredients

Throw the beer, moss, and sugar into a large pot and stir it around.

Step 5: Add Paint and Moss

Now comes the hard part. Cut the top off of a plastic bottle or grab a funnel and attach the mouth of the funnel to a balloon. Now pour your paint into the funnel and fill balloon about half full in it's collapsed state. (we'll inflate it with our mixture next)

Step 6: Pour Moss Mixture Into Balloon

This step is a messy one. Pour the mixture of beer and moss into a plastic soap bottle ( or better yet, a basting syringe). Attach the balloon to this and then squeeze the bottle to fill up the balloon. Watch the balloon as it fills to prevent it from exploding.

Step 7: Inflate

Now i might be best to accept that you probably eat sugar, eat lettuce (moss), and drink beer b/c this step is kind of gross but simple. Just inflate the balloon with your mouth to add more size so that the balloon will pop better when it hits a wall. Then tie of the balloon with an overhand knot.

Step 8: Go Outside

Now just repeat these steps for each balloon, and then go outside and launch them. Hopefully within a few weeks the moss will grow into the shape of the exploded splash with some nice moss drip marks.
( north walls tend to be better spots for moss to grow)

this project used ideas and resources from :

green guerrilla's green guerrilla's and moss graffitimoss graffiti