This herb can be farmed from 2 main areas the highest and most rewarding being Netherstorm here you will be island hopping to get the most possible Spawns.
The second place to farm this would be The Botanica but we are not going to be looking at this Area today.
Netherstorn is a bunch of Islands floating around to make the route as fast as possible a flying mount is strongly advised and a herbalish skill of 350 to begin farm this herb is needed.
Netherbloom spawn On the edge of island so to Farm the most Possible fly around the edge of each island.
If you Like this farming route or you have a better location yourself then let us know.