Contract worker David Alan Rees had used a ladder to go up on to the roof to clear the valley gutter on 19 July 2018, Mold Magistrates' Court was told.
The Health and Safety Executive (HSE) investigation found there was no safe system of work in place and Rees fell.
Robert Latham, who owns Knolton Farm in Overton, pleaded guilty to breaching s 3(2) of the Health and Safety at Work Act. He was fined and ordered to pay costs of £3,922.
HSE inspector Mhairi Duffy said: "Those in control of work have a responsibility to devise safe methods of working and to provide the necessary information, instruction and training to their workers and contractors in the safe system of working. If a suitable safe system of work had been in place prior to the incident, the death could have been prevented."