I have planted a lot of trees with a planting bar, but success is often tied to size of root system. If you plan to plant seedlings (2-0, 3-0, or 4-0 stock) their root systems are fairly meager, and you can get away with it. But take on some heavy transplants like Musser's 2-3 or 3-2 , and a planting bar can't possibly make a hole big enough. I use a top quality round pointed shovel. Turn the shovel around backwards so the end of the handle is aimed at your breastbone. In that position the blade is vertical. Move to the side (get the end of the handle off your chest), drive the blade down with your foot. Lean forward on the handle, kicking up a clod of dirt, and slide your hand down to the gooseneck. Grab the gooseneck, pull the clod up, and slide the tree roots into the hole against the back wall of the hole. Still grasping the gooseneck, pull the shovel blade out of the ground, and the clod of soil will drop right back down into the hole from whence it came. Stomp hard to eliminate air pockets. Repeat 999 times. Many Christmas tree growers (but not all) really like the auger method.