Green’s Dictionary of Slang

greengrocer n.

a prostitute.

1773		Harris’s List of Covent-Garden Ladies 51: She has been at Portsmouth in the laudable calling of bum-boating, more politely stiled a green-grocer.
1820		Morn. Post (London) 30 Oct. 4/1: The ‘Ladies’ [...] consisted of [...] some dozen bakers’ qwives (reckoning thirteen to the dozen — but no reflections!) green ‘grocers’ and publicans’ wives.