Which Mayor will be the Pumpkin King in 2018?

Hauraki District Mayor John Tregidga with two pumpkin seedlings before the 2018 Carnival.

Hauraki District Mayor John Tregidga has been challenged by Hamilton Mayor Andrew King to grow a giant or miniature pumpkin.

Mr King laid down the challenge to all Waikato mayors before the the ninth annual Great Pumpkin Carnival to be held at Hamilton Gardens next year on April 8.

Mayors will show their giant or miniature pumpkins as part of the celebrity section of the carnival.

This section consists of a weigh-in, with a funky challenge such as painting or carving a pumpkin — but not all tools are equal, Carnival spokeswoman Jenny Rowden said.

"What challenge will we set for our celebrities at the 2018 Carnival? It will be something funky and spectacular."

The Hamilton event has the Australasian record of a giant 789.5kg pumpkin grown by Tim Harris of Morrinsville.

"We are the only Pumpkin Carnival in New Zealand registered with the Pumpkin Commonwealth in the USA. Any record we hold will be officially recognised," Ms Rowden said.

This month is ideal to start growing pumpkins for the contest, she said.

Pumpkins take about three months to reach maturity and need a full sun spot out of the wind.

Miniature pumpkin varieties are grown the same way as regular-sized pumpkins, in up to a metre of soil and good compost, manure and dolomite.

When it is a football size, cut the pumpkins from the vines, leaving a little of the vine attached.

Pumpkin carving is elevated to an artform at the carnival with people competing for the best decoration.

Pumpkin races will also feature.

"We have a 4m track ready for everyone to mount any pumpkin on wheels and see who gets to the finish line first," she said.