Board Thread:Plants vs. Zombies 2: It's About Time/@comment-24908640-20140610113339/@comment-24760547-20140616005619

Jellifish13 wrote: The only way to collect keys is to complete the Gargantuar level. So do that then just skip the rest. And you don't even need to do it in assending order. So if you get one key, you can just wait till Dark ages if you really want...

Also if Pea-Nut is what it really is, I would be so happy, I don't know why... But it sounds cool/helpful I think he means the keys to open the gates. If that is the case, I would suggest doing endless levels a bunch to collect keys.