A Halloween Event started October 27, 2014. If you collect enough candy by harvesting your Main Farm within the time limit, you will win the reward. The amount of candy you have to collect depends on your level in the game.
Big Farm celebrated Halloween on the forums with an image hunt.
People awoke to a slightly different farm on October 31st, 2013. All the workers walking around the farm had turned into ghosts and stayed that way until the clock hit midnight where they reverted back to their usual selves.