Heaviest Qld pumpkin weighs in at 204kg

Figuring out how to grow the fattest, heaviest pumpkins has been Geoff Frohloff's passion for almost three decades.

"It's my hobby - I just like to see how big I can get them," the 60-year-old Queenslander told AAP.

Mr Frohloff's 204 kilogram Atlantic Giant pumpkin was crowned heaviest of them all at the Royal Queensland Show competition in Ipswich on Saturday.

It took about three months to grow the vegetable, which will be on display at the Brisbane show in August.

But it isn't the biggest one the fourth-generation Minden farmer has grown.

"Eleven years ago I had one that was 300.5 kilograms," Mr Frohloff, who has been entering pumpkin competitions for 27 years, said.

"That was also a big one."

The key, he says, is good seeds, soil, rich compost and "a lot of tender loving care".

But despite their impressive size and colour, the massive pumpkins aren't that tasty.

"One guy told me some years ago that he tried one and he said it was real sloppy," Mr Frohloff said.

"I think they'd make a real good soup."

The Royal Queensland Show's pumpkin competition was held early this year to take advantage of premium pumpkin growing times.