Magnolia Trees

There are two large Magnolia trees in my front yard. They are 40 feet tall. The problem is that they shade the yard and the grass does not grow. Also during this dry spell they shed some of their leaves which adds to the diminishing grass. What would I give up if I had a choice: the trees or the grass? I am sorry to say that I would give up the grass. The Magnolia is a beautiful tree. It takes a long time for one of these trees to reach the size of these.