The RHS's chairman of assessors has told Chelsea Flower organisers he is going to resign, while a leading garden exhibitor has criticised the judges and the best in show winning garden after failing to win the event's top award.
Chief assessor Andrew Wilson, an RHS judge for 17 years, said he had also submitted a complaint to the RHS about the quality of feedback he received after winning a silver gilt medal rather than the gold he sought for his Cloudy Bay-sponsored 'Fresh' garden.
Wilson, who led an assessment team for the event's 15 show gardens, said: "I'm in the process of resigning because of the way feedback on this garden was conveyed. It's not sour grapes but it was unacceptable feedback, and I'm saying that as someone who delivers it. I take a lot of time to give feedback as a judge in other situations and I felt the points raised missed the spirit of the garden."
He added: "I've also enjoyed making the garden and would like to design a show garden on Main Avenue at Chelsea and wouldn't be able to do that if I remained a show garden assessor."
Wilson said he was criticised for lack of attention to detail, having chairs too close to the back of the garden, failing to make best use of the garden's position on the showground and having a roof that was out of proportion to the garden.
Wilson is rewriting the RHS judging system and Chelsea gardens will be judged retrospectively using his "more scientific" ideas, but he said he did not know where his planned resignation left that now.
This is the first year judges or assessors have been allowed to design gardens too, on the proviso they exhibited in a different category to the one they judged. Assessors pre-judge the gardens and make medal recommendations before before judges look at the plots.
Meanwhile Wilson had to defend judges against an attack from Daily Telegraph garden designer Christopher Bradley-Hole, who was bookies' favourite for the coveted best in show prize but lost out to a unanimous verdict to the Fleming's Australian garden.
Bradley-Hole said the Australians' solar panels were "ugly" and the planting "unsubtle", adding: "Comparing their garden with mine is comparing apples with pears. I greatly admire parts of the Australian garden - they come year after year from Melbourne at huge cost and there's a lot to like in their garden this year.
"There's a impressive depth to the pool and good use of rocks in the structure but other parts are not quite so good and if that garden is overall better than mine, then I'm a Dutchman."
He added: "I think the RHS will have to rethink having a best in show at Chelsea unless it is very clear which it is. I'd be happy with an open system where the show gardens are rated from one to 15 but the sponsors wouldn't want to be ranked as twelfth best, and I understand that the RHS need to keep sponsors happy."
He said he would return to Chelsea but only to "make the same garden again and again until I win best in show".
He also complained that, having told judges his garden was designed for "contemplation", they came along as a "15-strong pack" and "only one looked at it on her own", saying: "That goes against the brief."
He added that he said the garden should be looked at and not walked in but one assessor "walked all over the garden", and asked: "Would they do that at Kyoto? Why would they have someone be so ignorant as an assessor?"
Wilson said the Australian garden was voted the best in show unanimously by all seven RHS judges involved but he personally placed Bradley-Hole next. He added: "He didn't receive feedback, he gave it to us."
RHS director general Sue Biggs said: "I hope Andrew does not resign because he's a fantastic judge. He's a great supporter of the RHS and a great garden designer and judge."
On Bradley-Hole she said: "Christopher is one of the world's best garden designers and we're honoured to have him at Chelsea. A different seven judges might have come to a different view. But this type of row does no harm."
Garden writer Peter Seabrook said: "As an exhibitor and a true Brit you know what you're going in for, and whatever happens you bite your lip and keep your counsel. I've been reduced to tears by what I believed to be unfair judging but that's life."
Kelways managing director Dave Root, who supplied the Australian garden with plants, said: "I've not heard a bad word about the Australian garden other than from Christopher."
The centenary celebration show finishes on Saturday.