Donna and Colin Craig-Brown of Ngāhinapōuri have named their 7.9-kilogram potato 'Doug'.
The Craig-Browns had no intention of growing a large potato, Colin tells Jesse Mulligan. Doug was just "one of nature's pleasant surprises".
"I had no idea he was growing there and I don't know how long he was there because I was walking over top of him all last cucumber season.
"It's just one of life's happy little moments, you know? Mother Nature has just bestowed this glory upon us."