Investigators said officers spotted the plant outside of a Bedford, England, home and the elderly couple told them they had purchased the plant at a flea market, not knowing it was a marijuana plant, the BBC reported Tuesday.
Police said the plant was seized and the couple will not face any legal action.
"Seized today. Elderly couple bought shrub at car boot sale, tended carefully -- biggest cannabis plant we had seen!!" Bedford Police posted on the department's Twitter account.