Campaigners say they have decided to end their near-15 year battle, with leader Gavin Blackman predicting the development would make inevitable further house-building over Wellhouse Lane up to the A34 and Three Maids Hill junction.
Mr Blackman, chairman of the Save Barton Farm Group, said legal advice on challenging the outline planning permission for 2,000 homes was unlikely to succeed.
The costs could be upwards of £50,000, said Mr Blackman.
He said: “We could not raise the funds and there was no guarantee we would be able to. We wanted to take it forward but we could not afford to.”
“The feeling now is that Barton farm is a done deal. The decision now is whether we become Shape Barton Farm rather than Save Barton Farm. I don’t want to be part of Shape Barton Farm. I don’t care what it will look like.
“I don’t think people are clear on what the impact this is going to have. I’m disappointed and perplexed there is not more fuss being made about it.”
On Barton Farm Two, he said: “It will go further. The infrastructure will be there. There is nothing to stop it going further north.”
Mr Blackman said he was still interested in national lobbying to alter Government policy to encourage more brownfield development.
Mike Emett, development director at Cala Homes, said: “I’m pleased we will now be able to get on and deliver the housing the city desperately needs.”
Some 800 of the 2,000 homes will be social housing available for rent by people on the city council waiting list.
Cala expects to undertake a public consultation in January before it submits a detailed planning application in the middle of 2013.
Mr Emett said he hoped to be building by spring 2014.