The Queen viewed Diarmuid Gavin's garden with its coloured balls

The Royal Horticultural Society (RHS) says two key themes this year are a focus on foliage and the colour green.

That colour, a garden staple, was emphasised for the 2004 show along with more muted flower tones.

The Queen also met TV gardener Diarmuid Gavin whose show garden contains hundreds of coloured balls.

CHELSEA 2004 600 exhibitors 21 show gardens 10 'chic' gardens 4 city gardens More than 100 floral displays

Called 'A Colourful Suburban Eden', it contains a series of multi-coloured metal spheres said partly to be influenced by Damien Hirst's spot paintings.

Mr Gavin said: "It's a garden for children and an experiment."

The sold-out show is open to RHS members from Tuesday and the public from Thursday.

The society celebrates its bicentenary this year and some displays pay homage to the botanists and plant-hunters who brought species to the UK.

157,000 VISITORS CONSUME 6,500 bottles of champagne 18,000 glasses of Pimms 5,000 lobsters 110,000 teas and coffees

Eco-friendly gardening and measures to encourage wildlife feature as well as sustainable and natural materials for gardens.

Exhibitors from the southern hemisphere have a strong showing with gardens from Australia and South Africa and the first New Zealand garden at Chelsea.

Inspired by Maori culture, it has a canopy of ferns, steaming hot mineral pool and a water feature carved in the shape of a water lizard.

Flatworm inquiry

Designer Kim Jarrett said the Queen asked about the garden's bird noise soundtrack, while the Duke of Edinburgh "hoped we hadn't brought any flatworms with us".

"They can get down under and eat the roots of the plants. We told him we hadn't."

The Earl and Countess of Wessex, Princess Royal and Prince Michael of Kent were also at the show.

Exhibitor applications are at an all time high and a new pavilion, the size of two football pitches, has been built to accommodate some of them.

The show will run over five days in 2005 but visitor numbers will remain about the same to try and address over-crowding.

A crime fighting rose named New Scotland Yard is also unveiled this year.

Rose is a thorn in side of crime

The Met has hailed the thorny red climbing rose - marking its 175 year anniversary - as an "ideal platform to illustrate garden security in action".

Meanwhile, the Horticultural Trades Association has released a study showing that vegetation may reduce crime rates on housing estates.

It showed apartment buildings with high levels of greenery had 52% fewer crimes than those with little or none.

The study was included in a new �1.7m campaign by the association, which urges Britons to reap the health benefits of gardening.

"Plantforlife" includes a 20-minute recommended daily allowance for people to garden or spend time around plants.

The campaign includes research showing one to two hours gardening a day could reduce heart disease and other chronic illnesses.