Well, as you've already spilled the beans, I hope they don't come after me for revealing this well-guarded secret (after all, we have already bought all their movies, multiple times), so just keep this photographic evidence between you and me:
--> It's New Zealand which is teal! <--
The problem was the budgets were getting tight and they skipped the correction needed to bring the colors back to Middle Earth (and the rest of the world). Here's the hidden-camera proof!
on location in New Zealand Middle Earth pre-vis correction