Plaguebloom only grows in three zones: Eastern Plaguelands, Western Plaguelands and Felwood, with the latter also being great for Gromsblood farming. Plaguebloom requires a skill level of 285 in Herbalism in order to pick it. In addition to Plaguebloom farming, these zones also have a bunch of Dreamfoil, while the Eastern Plaguelands even has Black Lotus.
