Don't Get Cheesed.
Get a Brie-lliant Game Tip here.
The Forbidden Grove Timing
The Forbidden Grove isn't always open.
It roughly works along the repeated pattern of 3 hours Open then 3 hours Closed, making it accessible 4 times in a full day.
If you're in the grove when it closes, you'd be whisked to the Acolyte Realm.
For a more accurate measure of the Forbidden Grove timing, you might want to check out Pooflinger's Forbidden Grove Timer.