I'd love to find a good nursery (gardens) near Harrison. Any suggestions?

Sure. Your two best bets with a vast stock of quality flowers, trees, shrubs and gardening paraphenalia would be Amodio's and Nabel's,Nurseries both located right near each other on Mamaroneck Ave. in White Plains. They are only about a two to two and a half mile drive from Harrison proper and I think you will be pleased with their offerings. Sometimes I just walk around there, particularly in Nabel's, on bright Spring days cuz it's soo cheerful and peaceful! :)