Who judges the judges? The seeds of change are planted at Chelsea

As the world's most famous horticultural event draws to a damp and blustery close today it seems that all has been far from rosy in the show garden over the past five days.

Organisers of the Chelsea Flower Show have been forced to bow to pressure from designers who have grown increasingly vocal in their demands for changes to what they believe is an arbitrary judging system.

Key among the gripes emanating from behind the begonias and Japanese pagodas is a lack of transparency, since individual judges can hide behind a cloak of anonymity. The Royal Horticultural Society's (RHS) development head Bob Sweet confirmed the system would be reassessed following the end of the show season at Tatton Park in Cheshire later this summer.

He said the way the show gardens were marked would be brought up to date, to match developments in judging elsewhere in the show such as in the floral marquee.

"We are reviewing the whole judging programme – we've not had a thorough review for 10 years," he said. "There are more sophisticated ways of judging now compared to how we looked at things in the past. Floral marquee judging has moved a long way, and on gardens we can do more," he added.

At present exhibits, such as Diarmuid Gavin's gold-medal winning Irish Sky Garden which commanded much of the media attention for its hanging pink pod, are assessed on a points basis. The crucial second round verdict rests on an anonymous show of hands from the eight judges, with the majority deciding if the designer wins a gold, silver or bronze medal.

Exhibitors are now calling for written rather than oral feedback to tell them where they went right – and wrong – with their gardens, the average price of which was £250,000 this year.

Designer Anne-Marie Powell, who was "disappointed" that her British Heart Foundation garden won only a silver at Chelsea this year, said: "I think any change is about time. At the moment the judging system is very difficult to understand or read and is not transparent. It's well overdue that the RHS updated their system.

"There have been some contentious medals this year and it is really good that the RHS is going to look at the system. Judging has been rangy – all over the place – this year. More than any other year in my experience."

Robert Myers, whose Cancer Research UK garden won a silver gilt at Chelsea this week, but who is not returning to the show in 2012 after six consecutive years exhibiting, said: "I hope they get the judging sorted out. The judging system has been around for a long time. It would be nice to think the RHS is making changes after pressure from designers. There are a lot of people who think the judging system is too opaque.

"Feedback is an issue. It is always nice to know after you put in so much work to understand why you have the medal you got. Paper feedback would allow you to understand how they've judged it because there's always a lot of theories that go around about results."

Inchbald School garden design director Andrew Duff said: "There's been a lot of controversy about judging. It needs to be totally transparent. It's a very small world and everyone knows everyone but that shouldn't matter. We should be able to judge totally impartially as long as it is transparent.

"The judging at the RHS is very, very closed. If the RHS perceives it to be so worthwhile they need to show how gardens are judged and give the public feedback on why Cleve West and not Luciano Guibbilei won best in show."

Beautiful blooms

The actress Vanessa Redgrave has launched the Natasha Richardson rose, named after her daughter who died in 2009. Pale pink, large and deeply cupped, it was bred to have high disease resistance. Robert Harkness, of the eponymous breeders, described the bloom, available through Dobbies, as "exceptionally beautiful with a heady, intoxicating scent". Sales will raise funds for the children's charity Make-A-Wish.