I grow them in a container. Vines were yellowing so I dumped it out and here they are! I grow from sprouted chunk of one potato (not slips, that didn't work as well), in 50/50 compost & soil and don't fertilize but do water if it doesn't rain for a week. Would only ever grow them in a container now, no hunting for them.
Oh, cool! So they’re quite similar to the Okinawan purple sweet potatoes which I’ve had before. Nice! Thanks for all the details.