I was called to look at relocating a holly tree. The tree is about 15 ft tall and sets 2-3 from a garage. It has two trunks both about 3-4" dia. There is no room for equipment so hand digging is how it's going to go. I really don't have a clue on how big of a root ball to make, please help. Should I put something in the hole before placing the tree in it's new location for feed or root stimulation?