Need help understanding moss needs.
I'm attempting to create a moss garden in an area of my garden that is partial to full shade. I already have some carpet moss and fern moss growing naturally. I'd like to propagate more varieties, and add moss cover to the concrete retaining wall and a hollowed out cedar log "planter".
My question comes down to the common recommendations that the pH of the soil (or substrate) should be acidic, between 5-6 pH. I'm very confused about this. How does one determine the pH of rocks & concrete, or wood? My understanding is that since moss doesn't have a root system, nor does it pull nutrients from the soil or substrate, why would the substrate pH matter at all? In fact, at our local botanical garden, moss artists painted moss art on a large sheet of glass, and it grew! Does glass have a measurable pH???
Also - Why is yogurt/buttermilk/beer generally recommended for moss paint (slurry)? What properties do these products have that moss like/or need? I read a old Fine Gardening article by a moss expert recommending NOT using the above products, as it mostly creates "moldy" moss, and what it's really doing is creating a short lived bio-degradable adhesive once the water content dries up and it becomes sticky. His recommendation for outdoor painting was using cheap wood glue (thinned with water) as an adhesive, and pressing on dry moss onto the substrate once the glue became tacky (15 mins). Then mist regularly with water once the glue sets. To me this made more sense, but I wanted to get more opinions from people that have painted rocks/logs - and were successful. Again, most of the recommendations I've read call for for the yogurt/buttermilk option, but this "expert" disagrees. So i'm confused about the right or best approach.
Thanks in advance,