Green’s Dictionary of Slang

(US) a prison; thus junk farm, a Federal rehabilitation institution.

1893		Sun (NY) 21 May 28/2: ‘If you are caught there you will be sent to the farm.’ ‘Wot’s de farm?’ asked Hungry Harry.
1900		‘Doss Chiderdoss’ ‘Of Good Address’ Sporting Times 20 Jan. 1/4: His epistle’s dated from a farm near Pentonville, / He’s no doubt compelled to give his right address.
1910		L. Esson Woman Tamer in Ballades of Old Bohemia (1980) 66: Chopsey: I’d sooner bring a moon than work for a dirty Dago. / Smithy: I don’t want to go up to the farm.
1924		‘Digit’ Confessions of a Twentieth Century Hobo 88: To be seen even near a freight train was enough to be pulled and landed on Brown’s Farm for thirty days.
1933		‘Goat’ Laven Rough Stuff 69: We found that Jackson is the place where the state Penitentiary or Farm is.
1943		W. Guthrie Bound for Glory (1969) 309: Give you an awful good chance to rest up out on the County Farm.
1958		H. Ellison Web of the City (1983) 49: No sense in my getting picked up and tossed in the farm.
1967		L. Bruce Essential Lenny Bruce 266: Thirty days on the farm aren’t gonna hurt you at all.
1972		G.V. Higgins Friends of Eddie Coyle 26-7: Dolan and Morrissey [...] were trying to get Artie Van turned around when he was up at the farm there.
1981		D. Jenkins Baja Oklahoma 53: Perhaps one day Dove might try something legitimate, if first he didn’t wind up making license plates on the farm.
1999		E. Bunker Mr Blue 287: The county farm was minimum security.
2001		D. Looser Boobslang [U. Canterbury D.Phil. thesis] 67/1: farm n. a minimum-security prison, usually situated in the countryside, where most of the inmates are employed in work-parties undertaking various forestry and farming projects.