Mack and Crack Auto Ready for one of the most potent new genetic lines in recent years? Mack and Crack Auto uses extreme genetics recorded at 25-30% THC levels to give you some of the most potent buds you can grow! She takes around 11 weeks from autoflower seed to harvest. Mack and Crack Auto was made by crossing The Mac (AKA Mac1 / Miracle Alien Cookies) with Green Crack. It’s rare to see autos with such extreme THC levels, suiting those looking to produce the highest potency levels.