If you are doing this is a terrarium, I would recommend just setting fragments of the moss onto the surface of the soil and not bothering with beer or buttermilk. Might even want to microwave the soil first to kill any fungal pathogens.

Keep the top partially covered to allow some air movement while maintaining high humidity. Mosses tend to grow abnormally (tall and thin) if kept under 100% humidity all the time. Water every now and then to keep the substrate moist. They grow slowly but should eventually fill in.

"Problems with growing moss" could be renamed "Growing moss" :)

I've tried a few moss experiments and can't seem to get anything right. Even transplanting it with the top 2" of soil and moving it 30ft away seems to kill it. From what I understand, moss is extremely resilient but extremely condition-dependant.

Well, from what i've picked up with trying to transplant moss is this...

Keep it moist the entire time. Sometime's i've let sit for a few weeks before i actually am ready for it to be used. It is of course dry and brittle by this time. I just crumple it up over the substrate i want to be covered in moss. After that is done, im make sure to keep it in good shade, (i grow under lights so it can get all the light they want) and also keep them moist constantly. It does take forever though.

If i use them imediately i put divide it up into little 1/2 inch squares and place it all around in a potted plant. The plant will give it shade enough to grow hopefully, some will survive, some will burn up. I also make sure to keep this stuff moist continously.

If im going to put them with my prized plants inside, under lights, i keep them in quarintine, and pick individual 'moss' out of the same type, and put them about a quarter inch away from each other in my clean potted planters. These are usually in high humidity, moist, warm environments. It takes forever here, but im learning, and also starting individual cultures for individual types.

I have yet to try and make any type of moss slurry, but will once i have time, and after i get a cheap blender.