I live in New River, Arizona. I purchased a house and inherited 3 large pony palms, each over 8 ft. tall. They are in big pots outside and we move them under our patio for the cold months (Dec-Mar). In the summer months (April-November), they sit in their large pots in direct sunlight. Will they survive the colder months (temps anywhere from 45-25) if I plant them in the ground? Pretty soon I won't be able to find a pot big enough or be able to move them by dolly....Any suggestions?