The top recommended places to farm this plant are Feralas, Un'Goro and Western Plaguelands.
I tried them all several times, lost some time running around and found only one plant. Maybe there were other people farming and picking them right in front of me but still the amount was rather low.
So I researched a bit, took some good advice and went down to Swamp of sorrows. Not only does it has abundance of Blindweed but also Fadeleaf and Liferoot if someone is need for those as well.
Most of the plants is located between whelps and horde base in the very center of the map, but as it turned out you can find some plants spread all over the map.
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