I know EXACTLY what you're talking about. I started making it my practice to always check Nightside in two realms any time I was passing through the Commons. Since that time, my wizards haven't felt shorted on Red Mandrake. The easiest place for me to find it has been Colossus Blvd, up towards the Gobbler King's castle. Of course, it's best to do this when a lot of other people aren't doing the same thing, but here's a good route:
Start by the left hand corner, as you are looking at the area from the entrance to the Gobbler King's castle. There is a spawn point here, whether you find one or not, go check -- then circle this space, over to the other corner, where there is also a spawn, near the Smith. Head up the road to the right, and circle around Baron Rotunda's place where ther are two spawn sites. Then, avoiding battle, cut over to the small island with the statue on it. There is another spawn on this island which is kind of hidden by trees. Once you've completed this circuit, change realms and reverse your direction. When you reach that lower corner, change realms again and go back.
Hopefully, this will help you get the blood moss you need. Good Luck!
I personally found the red mandrakes I needed in Nightside. Sure, it takes some time (about three hours for me to get everything I needed - though I only picked up a single blood moss on the way), but the spawns are close to each other, and you can, for instance, do your homework while hunting. :-)
can you PLEASE! add more respawn places for red mandrake. or at least make the drop chance of blood moss more often! i am going crazy trying to farm it!
I farmed about 50 red mandrakes yesterday and never found a blood moss with it. Have been stuck at DS quest forever! Guess I will keep farming until I have enough Red Mandrake to trasmute the blood moss I need.