Black lotus

i get this is a rare and highly saught after herb but its abit ridiculous to farm… 1 spawns 1 hour after last pick at any one of the 30 random locations with 30+ alliance and 30+ horde farming the same herb along with botters who spirit watch spawn points daily… so, like whats everyones secret to knowing when one will spawn? is there an add on that tells people when one was last picked? i am getting tired of mindlessly going around to each point trying to get one not knowing if one was picked just seconds before i arrived.