A Chelsea Flower Show 10-time gold medal-winner now says he is trying to grow the world's largest onion.
Medwyn Williams hopes his onion will be a record breaker
Medwyn Williams, from Anglesey, is growing it under artificial light on a bed of clay pebbles and feeding it with nutrients three times a day.
"It weighs 8lb or 9lb (3.5kg) right now but it needs to get to about 28in (71cm) and 16lb (7kg)," he said.
Visitors to the Gardening Show in Llangollen in July will have a preview when he shows some of its siblings.
Mr Williams, who competed for the last time at Chelsea after winning his 10th gold, said of his latest specimen: "It's gaining about a quarter of an inch in circumference each day.
"It's still got about three more months of growing - it's a bit of fun really," he added.
His stand at The Gardening Show at the Royal International Pavilion in Llangollen will also feature potatoes, carrots, swedes, leeks and radishes, and he plans to unveil his own formula of soil and composts.
"I used them for new potatoes and was enjoying them with my Christmas dinner," he said.
Mr Williams - who received an MBE for his services to gardening - first became interested in vegetable growing whilst growing up in Llangristiolus, Anglesey, in the 1940s when the family grew food.
"We were quite poor as my father worked on a farm but he was a very good gardener and in those days if you wanted fresh veg you grew them yourself - you can't eat flowers," he said.