Is it the correct Zilloween time frame? According to general forum post this is it, but there are no pumpkin seeds at vendors, nor will the old ones plant. :(
Unfortunately, the pumpkin seeds have to be enabled manually. We try to get this pretty close to when Zilloween activates for carving & candy badges, but we can't always get it exactly right (especially when Zilloween season starts at an awkward time of day in our timezone).