The squatters, who have been living on the land for four years, have cleared the area of rubbish and rocks and installed their own irrigation system.
Led by activist Omero Lauri, the squatters have handed over plots to families in need.
Rossella Paolini, left, plants a lemon tree with her relatives in their plot of land
Seventy-five families have already been given a share of the land.
"We believe that all people have the right to a piece of land for free," Lauri told the Associated Press.
The land is really owned by St Mary Major, the college of priest who serve the Vatican basilica of the same name.
Lauri and other activists met with the Pope in 2013 to discuss the land but the pontiff decided to turn a blind eye to the unlawful occupation.
"He said may God bless you, what else could he say?" Lauri told Italian news outlet Il Fatto Quotidiano after the meeting.
Squatter activist Omero Lauri sitting behind a table, centre, runs a meeting to assign plots of land to families
But local authorities are not as forgiving as the pontiff; Lauri said that the police have recently fined him £10,500 (12,000 euros) for building an unlicensed kitchen on the land.
Most of the novice farmers come from a nearby working class neighbourhood.
Rossella Paolini, who has recently taking on a plot said: "Since I was a child I've remembered my grandparent's vineyard, and this always stayed in my heart. Living in the city, you lose this."
Squatter groups and activists are frustrated with the housing crisis in Italy.
In 2014, Lauri also occupied the St Mary Major basilica for three weeks with 50 families who had been evicted from an uninhabited building nearby.