In my game, the only chunks (4x4 areas of tiles) in memory are the ones that the player is in. However, chunks need to have updates applied to them over time. A (likely) well-known example would be MineCraft: even if the player isn't in a chunk, the wheat still needs to grow over time.
My current solution is to call a method and pass in the time since the chunk was active.. but what if the chunk depends on nearby chunks for information, i.e. vines spreading or similar? Is there any reasonable solutions to this problem, or should I simply not depend on nearby chunks?