Giant pumpkins have been popping up in patches all over Queensland, but only one will be crowned the heaviest of them all.

Farmer Geoff Frohloff, from Minden, west of Brisbane, is hoping his smashing backyard behemoth will take out the title.

He is one of more than a dozen contenders in the Royal Queensland Show's giant pumpkin competition for 2014.

"They're called Atlantic giant or world's biggest pumpkin," Mr Frohloff said.

"They can put on 10.5 kilograms in 24 hours, or one day."

Mr Frohloff has been lovingly tending his crop in Minden since the beginning of the year.

He grows a variety of produce, but admits he has a soft spot for the supersized vegetables.

"I just love it," Mr Frohloff said.

"If it wasn't for their size I wouldn't grow them, they go rotten too quick."

Mr Frohloff has already produced several prize winners in the past.

In 2011, he managed to grow a giant pumpkin that tipped the scales at 300.5 kilograms.

He says as well as ensuring prime growing conditions, giant pumpkins also rely on a little luck.

"Every seed is different in a pumpkin - they don't all grow big," he said.

"One or two seeds in a pumpkin will grow a really outstanding one. You could have one in there that's 600 or 700 kilos."

Rosewood State High School horticulture students and teacher Paul Sanders, with their entry in a giant pumpkin competition. ( ABC News: Courtney Wilson )

Horticulture students from Rosewood State High School are newcomers to the competition.

Year 12 student Casey Hughes is hoping the school's first giant pumpkin could be a prize winner.

"It is still growing," he said.

"We're still treating it with love and care - a bit of TLC."

Fellow student Teenan Newsham says growing the perfect giant pumpkin has been difficult.

"Some of us have been attached to some of the pumpkins, like someone gets attached to an animal," he said.

"And then they've rotted away, so we've had to get rid of them."

'Lot of tricks we still need to learn'

Horticulture teacher Paul Sanders says the students have had plenty of pumpkins grow, but not all have made it.

"We've had to battle diseases, we've had to battle a lot of wet weather at some times, and those things haven't helped," he said.

"There are a lot of tricks to do with it, and a lot of tricks we still need to learn."

Grower Syd Haag, from Bundamba, west of Brisbane, may be able to help shed some light.

Mr Haag has been perfecting the art of producing giant pumpkins for more than 50 years.

"I've been connected with it since I was 16, so that's about 60 years ago," Mr Haag said.

"I think I know something about pumpkins."

Date change revives competition

Mr Haag even provided the seeds for many of the competitors in the Ekka's giant pumpkin competition.

The event had been steadily declining, but this year has attracted more entrants.

Its revival has been put down to a date change, which saw the competition moved to match pumpkin season.

Royal Queensland Show spokesman Brendan Christou says it had to do something to get the competition to evolve and grow.

"Obviously moving it into that prime growing season has really helped, and our numbers are now up to 19 this year, which is a resounding success for us," he said.

For the first time, the pumpkins are set to be judged outside of the Ekka.

Judging will take place on Saturday, May 10, at Ipswich, west of Brisbane.

The prize winners will go on display at the Ekka in August.