Why didn't Dr. Deaton or Ms. Morrell know where the Nemeton was? They're very powerful Druids and Deaton lived in Beacon Hills all the time, at least he should've known.
I'm talking about episodes 3x11 (Alpha Pact) and 3x12 (Lunar Ellipse).
I think the first question we must ask ourselves is how old is Dr D..
Only supernatural beings can see and find nemeton. Druids are helpers to supernatural thej are not supernatural beings.