Lichen Rock (Boulders)

For a unique look, check out these fascinating rocks. Ideally suited for growing lichen and moss. Biological weathering is the actual molecular breakdown of minerals. There are things called lichens (combinations of fungi and algae) which live on rocks. Lichens slowly eat away at the surface of rocks. The amount of biological activity that breaks down minerals depends on how much life is in that area. Moss and Lichen Growing Tips. To encourage the growth of existing moss and lichen, spray your rocks and any other garden items with a mixture of buttermilk or yoghurt (this can either be liquid, or the dry powder, reconstituted with water) and sheep manure. Individual boulders weigh from 30 - 100 lbs (14-55 kg) so most can be handled easily by 1 person.