If your garden angel is looking a little grimy, it may be time to clean that statue. You do not need expensive cleaners. You just need a some time and the willingness to put in a little effort. If your statue remains grimy after a simple washing, you want to invest in a stone-safe cleaner that removes mildew.
Fill a bucket with clean, cool water.
Dip a bristle brush in the water, and scrub the statue to remove dirt and residue that have built up over time.
Pour water over the top of the statue to further remove dirt.
Mix a solution of water and nonionic detergent. This is a special detergent that does not contain ions and has the ability to lift residues on stone. On marble statues only, you can use a mixture of water and ammonia. Brush with your bristle brush or a toothbrush. Rinse with water.