Sorry I didn't get back with you. I have muscadine grapes and get most of mine from Ison's Nursery in Ga. They have a web site with lots of info.
Some grapes need a polinator. I would suggest you plant a self fertile vine in close proximity.
I have two 25 year old James grapes that are no longer productive. They hardly produce any grapes at all. I can't seem to locate any new ones....
