There are a couple people if you search member's lists...one is in Canada

a site I found that may be helpful

Here is a link that might be useful: Growing Oca

I visited a guy near Raleigh, NC that had oca growing all around his garden. If I remember correctly he kind of just let it grow as a weed having lost interest in it as a food. In other words, I think it came back every year on its own and even spread to some degree, but not too aggressively. He gave me a plant the year before last. I'm waiting to see if it will reappear this year, but it might have succumbed to chicken scratching and/or voles.