A new high-flier joins Chelsea's gardening elite

So what do you have to do to win a gold medal at the Chelsea Flower Show these days? The answer, it would seem, is to build a bright pink metal pod inspired by a science fiction blockbuster, and suspend it from a crane.

The Irish Sky Garden, which features this very object, won the designer Diarmuid Gavin his first gold medal at Chelsea yesterday. He had the idea after seeing the Dublin animator Richie Baneham's work for Avatar. The inspiration for the planting and series of pools beneath it comes from the Giant's Causeway in Co Antrim.

The garden occupies the biggest site at Chelsea, as it also has to accommodate the crane that lifts the pod into the air. Sponsored by Failte Ireland and Cork City Council, it is – appropriately for an Irish garden – almost entirely green. Cushions of topiarised box and yew are interspersed with shallow circular pools and hummocks of grasses, such as Hakonechloa macra, which bend and billow in the breeze beneath cone-shaped hornbeams.

Gavin, who won bronze at Chelsea for his first garden in 1995, and silver-gilt for his gardens in 2004 and 2007, has made his name as an innovative – some say gimmicky – designer. He himself maintains he is merely building on a centuries-old tradition of garden features that astonish and delight. He describes his pod as the sort of thing that Willie Wonka might dream up – and describes the colour as "Wonka pink".

There is always controversy surrounding Chelsea gardens. In terms of popular taste, nostalgia will always win over minimalist modernism. The sort of hovel that would have given its pre-war inhabitants asthma or worse is perfectly acceptable, so long as it is decked about with hollyhocks and cottage-garden favourites, whereas a contemporary glass and concrete gazebo is condemned as "too much hard landscaping".

You cannot fault Gavin's planting, however. Walk along the steel path that leads through the pools and the pillows of box and you brush past plants that are at the peak of perfection. The pod itself is planted up with pale pink peonies and Actinidia kolomikta, with its rose-tinged foliage. The idea, said Gavin, who admits he is a bit scared of heights, is to make passengers feel safe and secure in their flowery carriage.

The pod contains two Lutyens benches, complete with seatbelts, on which are inscribed the names "Jack" and "Terry". Jack is the name of Gavin's father, who died in January, and Terry is his mother-in-law, Terry Keane, the Irish columnist and former mistress of Charles Haughey, who died in 2008.

"Terry was always a huge supporter of me being at Chelsea," said Gavin, "and Jack was always totally bemused by what I did. But he was very proud too. I like the idea that they're here at Chelsea, looking at each other."

Altogether, there were eight gold medals in the large show garden category, with Cleve West's design for The Daily Telegraph winning a gold medal and Best in Show. It is West's sixth gold medal at Chelsea, and an achievement that was also tinged with sadness as the 52-year-old designer's mother died last year. "She would have liked to have been here," he said.

Other winners of the RHS top award were Sarah Eberle, for the Monaco garden, Luciano Giubbilei for Laurent-Perrier, Jim Fogarty for Royal Botanic Gardens Melbourne, Laurie Chetwood and Patrick Collins for B&Q, Leeds City Council for its watermill garden and David Cubero and James Wong for Tourism Malaysia.