The Farm Girls where first seen in series 1 when the Mall Rats ventured out of the mall to trade batteries for food. They came onto a property and where confronted by many girls, and one of them was Alice.
They are next seen in series 2 with Alice and her younger sister Ellie. After they join the Mall Rats, the farm is run togther with the two tribes.
When The Chosen take over, the farm is seized and used as a place for slave labour. After their defeat, the farm is left in abandoned ruin. The remaining Farm Girls are presumably killed or taken away. Alice and Ellie are the only known members of the tribe still left.