That's hard to say. Exterminans told us a couple of months ago that there IS a holiday schedule, but it has never been kept. So... at this point your guess is almost as good as anyone else's.These events usually last between 2-4 weeks. The bigger holidays (Halloween, Christmas), generally last a month. Smaller events are usually shorter. But this event has so many variants, it might just last a bit longer. (I hope so, for some of the newer members!)
So I would have time to get more seeds of the Witch ones right?