Often I am asked why turf appears so weak underneath large shade trees. The usual answer is that the turf is not receiving enough sunlight to efficiently photosynthesize. Most turf requires about four hours of sunlight per day to remain health and not thin out. However there is another factor at play that may have a significant impact on the turf health and that is adequate irrigation. Healthy turf usually requires about one inch of water per week. Here’s the kicker- a mature pin oak also requires about one inch of water per week. This means if a property has a mature shade tree, the area underneath the canopy will require twice the amount of water other turf areas will!
Bear in mind this is one of four critical factors to have a successful stand of turf under a large tree. It is also important to fertilize regularly, properly prune the tree and it will probably be necessary to over seed the area annually in the fall with a shade fescue such as Rebel or Razor.