Once you have found Ghorim's Replacement, Baal Orun will commend you and reward you with this quest. When he finishes talking, choose to "say nothing" (unlike Baal Tondral, him talking to you does not mean you have permission to talk back). Climb over the wall behind the mashers, or go around it. Directly past here you'll find Balorn and the workers under him. Talk to him and agree to pay 50 Ore for the name of the man who buys weed. This opens up Cipher as a trader in the New Camp.
Now head onwards around the coast. Don't follow too closely or the Barrier will kill you. Eventually you'll see some Bloodflies and Swampsharks (avoid both), and after that you'll see Viron and his men. He won't just give you the weed, however; he wants you to eliminate the Bloodflies first. There are two groups (one on the ground, one hovering over the water). Use the usual strategy of luring them away to pick them off. If you bring them close enough the pickers will help kill them. Be sure to grab their wings as they have a fairly good trade value.
Once both groups are eliminated tell Viron you don't see any Bloodflies and he should be happy, and gives you the weed and 500 EXP. If he insists there are still more within 20 paces, eliminate the Bloodflies just across the water; there's a Swampshark near there, so beware. The weed pickers aren't strong enough to kill it if you lead it back to them, and if they die you can't complete this quest!
Once you've eliminated the Bloodflies you can do this route on a daily basis to round up weed. You can either deliver this weed like you're supposed to or else sell it to your fence in the New Camp (if you paid to find out his name).
If you want to do the right thing, head to the temple area. Go upstairs onto the wooden platforms and look for Cor Kalom's alchemy lab. Deliver the weed to him for 250 EXP. Return to Baal Orun, who will commend you. After he finishes tell him about the delivery to earn a Sleep scroll. You need this to impress Baal Cadar (simply cast it on one of his pupils).