THE Chelsea Flower Show kicks off this evening at a £280-a-head charity bash where the great and good will mix with celebrities and even a few gardeners. The champagne will keep flowing until the show closes on Saturday, rather than Friday — the extra day is a “first” in the show’s 83-year history.

The opening gala is a contrast to the politically correct green agenda claimed by many of the design gardens. Words such as “recycling”, “sustainable”, “wildlife”, “conservation” and “organic” pepper the descriptions of this year’s gardens — although how anyone can claim the high ecological ground for gardens which involve flying plants and people from all over the world is beyond me. Plant few wild flowers, use some recycled stuff and, apparently, it is OK to nuke the atmosphere with jet aircraft exhausts.

More convincing green credentials can be found in modest show gardens such as that of Sheddingdean Primary School. It is designed by the children, with a miniature house/compost bin, a woven chestnut perimeter, wood pile and simple planting. All the plants and features come from sources in Sussex and will return to the school after the show.

And the Fittleworth Horticultural Society garden, which makes no ecological claims, cannot have dented the planet’s ecology to any great extent. All the flowers and artefacts in this voluptuously planted garden come from members’ own plots — whence they will return.

“I wanted to make a garden which would make people think, ‘I can do that at home’,” says Beth Holden, its designer, who is at Chelsea for the first time.

For the fashion-conscious, colourful planting and, yes, balls appear to be major themes this year. Box balls appear in gardens by Kim Wilde, the former pop star, and Chris Beardshaw and Diarmuid Gavin, the TV garden makers. Wilde’s are offset by a pleasing slate sphere. Gavin’s appear amid a sea of lavender and spherical white pavilions backed by a wall of polished black marble. Beardshaw’s balls line a pool with a cloud-pruned pine from Germany at its centre and cylindrical hornbeams at the far end.

Gavin’s cool colour scheme contrasts with a euphoric wildflower planting by the Fetzer vineyard garden from California. The colourful style is echoed in the Cancer Research garden by Jane Hudson and Erik de Maeijer, who last year won the BBC/RHS people’s choice award.

Water weaves through plenty of gardens. In the stunning Merrill Lynch garden Andy Sturgeon has made a pool with square holes — voids — in the water. These cubes of voidness are echoed by a hillock of oak cube stepping stones interspersed with planting that make a Giant’s Causeway effect.

Another Chelsea veteran, Tom Stuart-Smith, has sheets of water falling into rectangular pools from an alley of weeping hornbeam. Rectangles of green and purple make a typically elegant Stuart-Smith planting, although I could not see how it relates to the riotous Italianate gardens of Trentham, which are supposed to have inspired the design.

Riotous planting abounds in the Great Pavilion, with displays from Jamaica and South Africa and several great British rose-growers, including Peter Beales, who celebrates his 30th Chelsea this year. He has bred a host of favourites over the years, including the scented, creamy-white, repeat-flowering climber Clarence House (at the request of the late Queen Mother), and the pink City of Oelde, a tough, repeat-flowering modern shrub.

Continuing the theme of first timers, Alan Titchmarsh will make his first appearance at the show. No, not that one — this is the “full, rounded and pink” rose of that name, bred by David Austin.

Other new plant launches include Coreopsis Crème Brûlée (Blooms of Bressingham) — a delicate-leaved plant with serrated yellow petals. Blooms had to keep the plants under 24-hour-a-day light and heat to bring them on in time for the show.

A final first comes from the Chelsea Pensioners, who live at the Royal Hospital where the show takes place and who have mounted their first garden. It commemorates the 60th anniversary of the end of the Second World War and it is an enchanting vision of “Blighty”, designed by Julian Dowle.

The pensioners grew vegetable varieties taken from a 1939 catalogue and surrounded them with a thatched village pub and garden complete with wistaria-covered arbour, a duck pond and a meadow speckled with scarlet poppies.

Jane Owen is presenting the official Chelsea Flower Show DVD (available through www.rhs.org.uk).

She answers garden questions every Friday at noon at the Gardening forum

Tickets for the Chelsea Flower Show may still be available via 0870 9063781