Man digs up 6.7kg kūmara in his New Lynn vege garden

Normally Richard Cowper grows carrots and silverbeet in his New Lynn vege garden, but this year was the first time he grew kūmara - and giant kūmara at that.

"I put them in as an experiment really, and I wasn't even sure I would get anything out of them.

"Then when I went to dig them, I saw a red tuber and thought 'oh great'. I went to pull it out and it was huge - and they just kept getting bigger. It was bizarre."

Cowper harvested five giant kūmara, with the largest weighing 6.7kg, and others weighing in between 1.5kg and 4.9kg.

"It was hilarious really. Digging them out I couldn't believe my eyes.

"Some of them looked fairly normal, but the big one looks a bit like a tumour or something you've had cut out of your body," he said.

Cowper said he had no clue as to what was the success to his kūmara-growing technique.

"A friend of my daughter's suggested I check for a pulse, while someone else said I should check the radiation in the soil.

"I don't know whether it is something in the climate this year that has triggered it maybe. It's a puzzle."

Despite their size, Cowper said the sweet potatoes still taste normal.

"I gave one of the big ones to the neighbour, but it comes with no guarantee," he laughed.

"I really don't know what to do with them. I suppose we will chop them up, blanche them and freeze them."

Cowper said he plans to expand his vege patch, after retiring last week, but hopes he can grow some normal-sized kūmara next season.