Roger Davies, who works at Hereford Wyevale Garden Centre, will retire on August 13. He turns 65 shortly after, having started at the centre when he was 16.
Centre manager Richard Debbage said: "Roger is the longest-serving employee not only in Hereford, but across the whole of the group.
"We thought it would be a great idea to mark his retirement with a party, which we are inviting customers to attend.
"Tickets will cost £5 per person and proceeds will be donated to Roger’s two chosen charities, The Meningitis Trust and Greyhound Welfare."
Davies said: "I am delighted the team has organised a retirement party for me and I am looking forward to chatting to visitors and sharing my memories with them."
The customer services expert was last year presented with a RHS gold medal for loyal service, as well as a long service award from the Garden Centre Group.
Call 01432 266261 to buy a ticket for the party, set for August 13.