Most alocasias will survive the 50's but it's not a great thing to have it go on for prolonged periods of time. Some will just go dormant in the 50's. Whether it will survive cooler temps like the 50's and below also depends on if the winter is wet, or dry. Dry winter is best, if the plant does go dormant or gets the top growth killed back by frost or freeze, the tubers left in the ground fare better in dry conditions and may rot it wet conditions. Usually alocasias knocked back by cold in winter will come back, but sometimes it's like starting over. I personally would keep it potted through one or even 2 winters, to see reliably how cold it really gets and for how long, before I planted it out
