Here is my personal route for smv nightmare vine farming. It is a little complicated but it hits all the important nodes that have the best respawns that I have found. Red marks usually have a cluster of herbs unless it is also being farmed by someone else. I'm also assuming you have the netherwing attunement done and can herb the Netherdust Bushes, which are a great source of motes of mana and fel lotus when not turning them in for the daily.
I usually do one run of this, hit up netherwing ledge for any bushes there, and then do this route again. Depending on how farmed it is atm, I can get up to 2 stacks of vine, a few fel lotus and 1-2 stacks of dreaming glory/terocone if I bother to pick those up.
Sorry if this is a repost =)