Auckland's Cornwall Park is better know for family picnics and weekend strolls than livestock auctions.

Next month farmers will head into the city as the park's woolshed hosts its bull sale, with 20 yearling Simmental bulls going under the hammer, which will help fund some of its operating costs like lawn mowing and fencing.

Farm Manager Peter Maxwell has overseen the farming operation for two decades, managing the Simmental stud alongside a flock of around 250 Perendale ewes.

He said the genetics of these "quiet" and naturally polled bulls without horns are likely to be in high demand.

"They have no horns which means they are less of a danger to people, and also to themselves," he said.

"We've had a breeding line for a number of years. People have been buying them for quite a few years privately in the paddock, but now we're running an auction.

"We have 62 simmental purebred cows calving, just over halfway through calving now. We have replacement heifers and service bulls, and we're selling 20 of our rising one-year bulls."

The bulls have been raised on the 72 hectare inner city farm, surrounding Maungakiekie One Tree Hill and bordering the suburbs of Epsom and Royal Oak.

With sustained strength in global beef prices driving a record-breaking bull sales season, there's optimism this year's auction will deliver strong results.

"I'd like to think that we can capitalise on that a wee bit," Maxwell said.

And what will they do with the money?

"There are plenty of expenses. The farmland helps assist with some of the other expenses. It's 72 hectares of farm and there's a large area of parkland which is mown, and gardens and trees, the yearling bull sale just helps defray some of the costs."

Cornwall Park was gifted to the city by Scottish entrepreneur Sir John Logan Campbell in 1901 and is today fully funded by the Cornwall Park Trust Board.

And for farmers who aren't keen to tackle Auckland's traffic, the sale is also available online at the Bidr platform.

The working Cornwall Park farm makes up around 40 percent of the parks total land of 172 hectares.

The auction is on 2 September, with preparations in full swing.

It's a busy time for the farm with lambing and calving underway. Maxwell said twins feature predominantly among this year's stock.