The key to planting a tree is - DON'T PLANT TOO DEEP. The hole should be dug to a depth that allows the first root growing off the trunk to be slightly above grade. You will notice that trees in the wild sort of have a "foot" with this root extending from the base of the trunk. The reason for this is that trunk material when buried will not convert to root material and the tree could be hampered in its health or even die.
Once the tree is in the hole at the proper depth, thoroughly water the hole. Next, pack the soil from the hole firmly around the tree and water in well. Make a small berm around the dripline of the tree with any excess soil as this will help force water to the root ball.
Questions? Feel free to contact our Tree Nursery