I was told to dip lichen (island moss as it's called in Germany) into barely thinned PVA and drop it into flock afterwards.
This came out:
(using Noch micro flock)
(using Noch Leaves)
Then I decided to give the hemp/sisal another try:
Pour a line of glue to a smooth surface.
Dropp pre-cut sisal/hemp fibres on it and carefully dip it into the glue.
Let it dry overhead to make the fibres stand up.
Paint it as you like (using an airbrush finishes this step in no-time!)
Brush the fibres with glue
Drop it all in the flock/leaves/foliage of your choice
Let it dry
Post-Fix it with Hair-Lacquer (or other sticky stuff)
Looks like this:
The result of two evenings: