By Jennifer Calfas 

"Dug," a contender for the world's heaviest potato, might soon become "Done," the vodka.

Colin and Donna Craig-Brown found the tuber underground in August while clearing a plot in their New Zealand garden for new seeds, and the couple submitted it to Guinness World Records.

The unexpected giant awaits the verdict while stowed in the couple's freezer to maintain its weight, which they recently reported as just over 16.7 pounds. The current Guinness potato record, awarded in 2011, is about 10.9 pounds.

And they have begun a discussion that's familiar to jumbo-produce growers everywhere: What's to be the misshapen mass's final fate?

It's too lumpy to create a cast a replica for posterity, says Mr. Craig-Brown, 62, and there's no way they would preserve it. The amateur distiller has another idea: Turn Dug into vodka.

"We're going to have a wake for him at the end of the whole process," he says. "I'm going to name the vodka Done, because Dug will be done by then."

Giant-produce growers typically don't have personal consumption in mind. After records are set and festivals are over, a giant's final stop can range from compost pile to seed harvesting to serving as a movie-set prop, says Kevin Fortey of Cwmbran, South Wales, the current Guinness record holder for heaviest beetroot.

Some people carve their giant pumpkins for Halloween -- or drop them from 100 feet in the air at festivals or blow them up with explosives.

Other growers donate their big veggies to food banks or farms. Mammoth onions, tomatoes and celery can taste good, "but just need a large family to feed," Mr. Fortey says. The 43-year-old health-board project manager made a chili sauce out of the world's heaviest beetroot, holder of a Guinness record he and his family set in 2019.

Patrick Teichmann of Poessneck, Germany, has grown giant vegetables since 2012 but doesn't eat them, saying: "I am an absolute carnivore." The 29-year-old, who grows these veggies full-time, stores his behemoths until the seeds ripen and composts the rest.

An artist has carved birds and flowers into one of Mr. Teichmann's massive marrow zucchinis. The grower filled another marrow with about 66 pounds of mostly minced meat and cheese, and it became the largest portion of filled zucchini -- at about 137 pounds -- according to the World Record Academy, a competitor to Guinness that certifies measurable world records.

Christopher Qualley, the Minnesota-based Guinness World Records titleholder for world's heaviest carrot, tried to salvage the 22.4-pounder for seeding. It ended up rotting. Before he placed it back in the soil to try to recover it for seeds, a relative took a bite. "She said it tasted like a carrot," he says.

"There's no real purpose for a giant vegetable as far as supporting a community or feeding people," says Mr. Qualley, 38, a real-estate agent who got into the hobby first with giant pumpkins.

He wouldn't make a pie with a giant pumpkin, he says: "They're gross. They're stringy."

The Great Pumpkin Commonwealth, an organization with clubs around the world, sets rules, standards and regulations for many pumpkin competitions. Andy Wolf, a county public-health sanitarian, was crowned the North American champion this year with his 2,365-pound pumpkin, which then went on a brief tour before coming home.

Mr. Wolf, 42, plans to collect its seeds and distribute some to giant-pumpkin-grower clubs world-wide, he says.

The carcass will go partly to his 67-year-old aunt, Vicky McKinney, who says she makes five to 10 gallons a year of pumpkin wine. "It turns into the most amazing Riesling," she says.

Jumbo-produce growers dedicate considerable energy into creating the perfect environment, saying the right soil and seeds, and attention to pests and diseases, are crucial.

The Craig-Browns didn't do any of that, having no intention of growing a record spud. They stumbled upon Dug in what most recently was a pathway between strawberries and cucumbers. They had grown potatoes there previously but not for at least two years.

"It just went along doing its thing completely unnoticed until we uncovered him," says Mr. Craig-Brown, who works on the couple's hobby farm. "We looked at it in amazement and said, 'This is crazy.' I scratched it and tasted it, and said, 'That's a bloody potato.' "

It was 7.9 kilograms on their metric spring scale, or 17.4 pounds.

They submitted a Guinness World Records claim to determine whether Dug was a global winner -- a process that can take months -- and took it to a seed store for a second weigh-in and found it was just over 16.7 pounds. Worried Dug had lost weight from wounds suffered from a hoe and gardening tongs, the couple stuck it in a freezer to maintain its mass.

Weeks later, they pulled Dug out for an official weigh-in for Guinness with two unaffiliated witnesses -- the retail assistant and store manager at their local seed shop. They wouldn't disclose the results of that more recent weigh-in, but confirm it has lost some weight since they found it.

They then discovered the official Guinness weigh-in requires a qualified professional -- like a horticulturist or botanist -- to identify and measure it, so they must redo the weigh-in, they say.

A spokeswoman for Guinness World Records says it received the couple's claim and is waiting for evidence to review.

"Sometimes these world records are flukes," says Mr. Fortey, the Wales-based grower, whose father started pumpkin competitions at a pub until they couldn't fit through the door, "and there are real surprises."

Today's heaviest-potato titleholder, Peter Glazebrook, doesn't think the Craig-Browns will surpass his 10.9-pound record because he doesn't think whatever they found is a spud at all. Dug's rough surface markings and growth shapes, he says, aren't typical of a potato.

"I think he will not be able to substantiate his claim," says the England-based Mr. Glazebrook, 77, who has broken -- and re-broken -- Guinness records for longest beetroot, heaviest potato, heaviest onion and heaviest cucumber, among others.

One has to work deliberately to grow a giant, he says in an email: "There is no way anyone can suddenly 'find' without trying a vegetable almost twice the size" of the record holder.

Mr. Fortey, who has seen photos of Dug online and communicated with other growers in a Facebook group he runs, says it looks like a potato and "I think the consensus of opinion draws it to a potato."

The couple responds that the verdict is up to horticulture professionals.

Dug's destiny is vodka. It will be a new challenge for Mr. Craig-Brown, who has made the liquor only using sugar before: "We might get a bottle or two out of him."

Write to Jennifer Calfas at Jennifer.Calfas@wsj.com