Step by step pictorial ,if you want i can add a nominal write up as well but its pretty easy to follow.
Old tip from Keith at our club for basing,swapped from plaster to Coving adhesive or Tile adhesive much tougher and cuts chipping from ware and tare down to next to nothing.
While the plaster/adhesive is still wet and tacky swish the base in your sand bucket,saves having to glue it on later.
Applying the marsh grass:
Push the end of a matchstick into the filla and give it a little spin,this creates a nice indent where you want the grass to sit,now take a pinch of grass and fold it in half,now cut the bottom/fold off and dip it in white wood glue.Just push it into the hile youve made and nine times out of ten it will just sit bolt upright while drying.
Once dry cut the grass to size and push the middle out to spread the grass slightly.