mossy/lichen covered rocks

My father in law pointed out that the zillion rocks we have out here are often covered in lichen and that some garden places sell those for big bucks to people landscaping their homes!!!

what would be some way to encourage the growth of lichen on some of the more attractive large rocks?

not sure about lichen but moss can be encouraged to grow with yohgurt

scrape a little off the rocks here and there, gather a couple of cups.  Dump it in a blender, add a teaspoon of molasses and a cup of lukewarm compost tea.  Turn on the blender.

Take the soup outside with a wirebrush and a paintbrush/rag/or sponge.  Find a rock you'd like to see covered with moss and lichens, give it a few swipes with the wirebrush on the north side of that rock.  Paint it with the soup.  Paint it a couple of times a day for a few days

The soup is a mix of nutrients and spores.  The wire brush removes indigenous lifeforms to make way for the spores you are depositing.  The north side is shaded, won't dry out as quickly.  Repeated application maintains moisture and nutrient levels and also reinoculates the area giving your spores a competitive advantage.

My mother told me and i think the builder, my long a dearly dead friend keith Oníons, told her that if you build a new feature onto your house a chimney or somthing and you want it to lichen up so it stops looking so different from the rest, you dilute manure and paint it on and wait. agri rose macaskie