I made two of these from some bare root amelanchier arborea that I received from the Missouri department of conservation.
Solo rock planting
The rock
Serviceberry on the rock
Wrapped up!
Filled the inner area with sphagnum and shohin size soil. Normal bonsai soil outside of the Saran wrapped area.
Serviceberry forest featuring a ROR.
Rock in an Anderson flat, serviceberries hanging out back.
Done. Just used some wires and sphagnum to hold this one in place. Not sure how successful it will be.