» Fri May 27, 2011 9:08 pm
That UESP link will also lead you to a map that shows where they are. Note that the area with most total plants has them fairly scattered around, but there are a number of locations in the Blackwood area where they grow in clumps.
Also since you're not asking about the Dragon's Tongue, I'd suggest you try handing those in before you go looking for the Redwort, as you may get let off.