Ok so I'm a little confused as to which farm you mean if you mean the farmstead/ste's place you need to have freed him from viccoria before searching the forest path.
If you mean the old barn, you need to finish the werewolves story to the point of curing bernard and logan then talking to bernard (when He has 3 hearts) about searching for him.
(Also Victoria is found in the cave in the area after the grill bridge)