The Boningale Nurseries chairman said: "I've been lobbying that the Government should do one through the horticulture round table as part of garden cities projects and green cities.
It would be quite a number of years away - to do it properly takes a long time but the UK would be capable of doing exceedingly well. It would take a number of years to plan and a long time to get the Government to be into it."
Edwards said the AIPH recently visited an expo in Milan that attracted 23 million visitors while the last AIPH-sanctioned horticulture expo in Qingdoa, China, attracted six million visitors to 55ha in the new city in 2014.
He suggested that the UK expo theme could be about "living comfortably in the landscape". The last UK garden festival was in Liverpool in 1984.