How deep and wide a whole should be to plant a foxtail palm what kind of soil should be used to plant the tree?

You should dig a hole twice as deep and wide as the palms pot then fill with a well draining soil mixture until the hole is half full. Then place the palm in the hole and fill with the remaining soil mixture. Also a good idea to add a 20-7-7 NPK fertilizer about six inches below soil level. Best to plant in the late spring to early summer. Good luck.