This ensures that the point where the top-most root emerges from the trunk remains at or slightly above ground even if the root ball settles. Cover the sides of the root ball with mulch, or perhaps soil. Form a water ring (berm) from mulch only if trees will be irrigated with a hose. The water ring is not needed if trees will not be watered after planting or if trees are irrigated with a low volume head. Water rings made from soil can lead to problems because the soil is typically pushed over the root ball later. Roots will grow extremely fast into the mulch and surrounding soil and trees establish quickly using this planting technique.