you need to rescue Ste to find the farm, then once you do that he tells you how to get there from the underground. after that its just you constantly wondering around the new area till you actually find the farm
He's located in the same cave as Korg. (Vicoria's cave) I have no idea how to find it; sorry. Once you complete the quest, wait a day and then return to look into the cell. You'll find Vicoria messing with a new prisoner, which you can then go and talk to her about, instigating a quest to free said prisoner.