You can technically call it both the Garden State and The Produce State, But it is prefered as The Garden State, Even though you are totally right, Here is a cute little story, Now i am older, In kindergarten I had a show about USA states, I got New Jersey and i had to say a cute little quote like, "New Jersey is popular because of its great Produce! So you are right but it is prefered to be using The Garden State, Rather than The Produce State.