A to Z of the Chelsea Flower Show

A is for A-list. The Chelsea Flower Show marks the start of the London "Season", which, roughly translated, means it is seen by people who care about these things as a cross between a rather grand garden party and a photo opportunity. Celebs will be crawling all over it like aphids on a rosebud. It will also have the best plants, the top growers and some of Britain's most talented garden designers.

A is for A-list. The Chelsea Flower Show marks the start of the London "Season", which, roughly translated, means it is seen by people who care about these things as a cross between a rather grand garden party and a photo opportunity. Celebs will be crawling all over it like aphids on a rosebud. It will also have the best plants, the top growers and some of Britain's most talented garden designers.

B for black, as popular with garden designers as it is with fashionistas. The first black hyacinth, the extraordinary "Midnight Mystique", is being launched by Thompson and Morgan. Listen for the squeals of outrage when buyers see the price, £7.99 per bulb - 10 times what is normally charged for a hyacinth bulb. There's also the International Black Plant Society (yes, really) who will be highlighting the delights of such plants as Heuchera 'Licorice'. While it's a very dark day over at the Lalique Garden where it's all plants with black or very dark flowers, including Actaea simplex 'Black Negligee'. Good in beds, apparently.

C is for chocolate, as in the Roald Dahl Foundation Chocolate Garden, which has chocolate-coloured and even chocolate-scented plants, a water feature that looks as if it's running with melted chocolate and a "gloop pool" inspired by Charlie and the Chocolate Factory. C is also for crowds, of which there will doubtless be plenty.

D is for drugs. No, not Cannabis sativa, but an exhibit by the Royal College of Pathologists that explores six familiar plants and their role in fighting disease. The six are: willow (aspirin), foxglove (heart disease), yew (ovarian cancer), vinca (leukaemia), artemisia (malaria) and tea tree (microbiology).

E is for edible, or, to be strictly accurate, "exotic edibles" as demonstrated by the chef Raymond Blanc, who has collaborated with the Oxfordshire-based Newington Nurseries on the Asian Garden, an exhibit that aims to show people how to grow Malaysian specialities such as lemongrass and ginger in the UK. (See also V for Vegetables.) And E is for estate agents, notably Savills, celebrating its 150th anniversary with a garden inspired by the 18th-century Grand Tour. Sadly, there won't be a real estate agent on site to point out the period features, but at least viewing won't be by appointment.

F is for the Fetzer Wine Garden, an organic garden sponsored by a Mendocino County, northern California, vineyard, which admirably demonstrates that pottering around your plot is much more pleasant when accompanied by a glass of zinfandel or merlot.

G is for Diarmuid Gavin. If gardening has any claim to be today's rock 'n 'roll then Diarmuid is its Liam Gallagher. His garden this year is described as being a "contemporary communal garden, possibly for an apartment block". Let's hope Bunny Guinness doesn't move in: the two designers fell out last year in a well-publicised spat. It's rumoured that Diarmuid has calmed down and currently favours a return to traditional gardening and herbaceous borders, but just to be on the safe side, the RHS has prudently placed him next to Terence Conran's peace garden (see W).

H is for Hilliers, the nursery and garden centre people, who are competing for their 60th consecutive Chelsea gold medal this year. There is no limit to the number of golds that can be awarded each year - sometimes only a couple of show gardens get the prize gong, other years it's four or five. But there are always the silver-gilt, silver and bronze medals to hope for. H is also for Honda, which is running a competition to win a top-of-the-range lawn tractor. The tractor may be in the team colours of the BAR Formula 1 racing team but don't make jokes about having to guess the weight - the Honda team is still smarting from being banned for running an underweight car in the San Marino Grand Prix. And H also stands for horticulture, as in the Royal Horticultural Society, without which there would be no Chelsea Flower Show.

I is for information technology, the sort that allows you to give up commuting to the office and work from home, as in the SoGo Garden. This Microsoft offering includes a workpod that transforms the garden from a zone of pastoral inactivity into a fully networked micro-office using wireless connectivity. The Merrill Lynch garden, designed by Andy Sturgeon, is also a workplace, with a glass-fronted office at one end.

J is for the Australian garden designer Jack Merlo, the new kid on the block this year, whose contemporary, outdoor-room design, entitled Float and sponsored by Fleming's Nurseries, won the Award of Excellence at the Melbourne International Flower Show last month. J is also for judging, a complex and arcane process involving RHS teams with names like "Floral B Committee" (Hardy Ornamental Woody Plants) headed by a man in a panama hat. How to spot a judge: he or she will be the one casting furtive glances over their shoulder in case an irate exhibitor wants to berate them about not getting a gold.

K is for Kim Wilde, who proves that there is at least one tenuous connection between gardening and rock 'n 'roll. She's a co- designer of the Cumbrian Fellside Garden, which features wild flowers, slate and a water feature that mimics a fellside rivulet. Kim herself isn't totally out to grass these days: she's performing alongside the Stranglers and Toyah at Culzean Castle in Ayrshire on 12 August. All together now: "We're the kids in America, woh-oh..."

L is for Terry Lloyd, the ITN journalist killed while reporting on the war in Iraq in 2003. He is commemorated with a new variety of helenium called 'Chelsey', launched by Rougham Hall Nurseries. For each plant sold, a donation will be made to the British Red Cross International Disaster Fund. Chelsey is the name of Terry's daughter, who began the fund-raising campaign as a way of thanking the Red Cross for bringing home her father's body.

M is for the Message in a Bottle exhibit - no, not another Eighties pop song ("Kids in America" still going round your brain?), but an SOS to the world from the Royal Botanic Gardens on behalf of rare and endangered plants. It includes the cabbage tree from the Robinson Crusoe Islands and what might be termed a pinosaur - the prehistoric Wollemi pine, discovered only 10 years ago and Kew's prize exhibit.

N is for nettles, as nurtured over the past few months by garden designer Claire Whitehouse for her Real Rubbish Garden, sponsored by the RSPB and Sita Environmental Trust. As the name suggests, the garden uses items that have been reclaimed to attract wildlife such as the declining house sparrow. It's one of many exhibits at this year's show which explore sustainability and other environmental issues.

O is for organic and an initiative led by the Henry Doubleday Research Association. The Organic Food for All exhibit shows that you don't need some poncy potager or walled garden to grow your own food: you can produce organic vegetables regardless of space, income or previous experience.

P is for photography, and a new trend this year which sees two show gardens - Room 105 and The Gallery Outside - designed as outdoor photographic galleries. P is also for portraits by Patrick Lichfield, featured in The Gallery Outside. And P is for pool, not the turquoise tiled version, but a natural swimming pool in the Moat and Castle Eco-Garden. Expect to see at least one bikini-clad female in it for the benefit of the television cameras before the show ends.

Q is for the Queen, who dutifully tours the show each year on the afternoon before it opens, accompanied by other members of the Royal Family. Prince Charles isn't doing a garden this year, so the chances of eavesdropping on any more rude remarks about BBC royal correspondents are much reduced. Shame.

R is for recycling, the theme of a garden designed by the composting woman's crumpet, Chris Beardshaw, to highlight the Wrap (Waste and Resources Action Programme) recycling campaign. R is also for restios (Cape reeds) which have taken over from grasses and bamboos as one of the most achingly fashionable plants of the moment. See them on the Big Grass Company stand in the Great Pavilion.

S is for Saturday opening, the first in the 83-year history of the Chelsea Flower Show. The RHS has finally realised that some of us have to work for a living and only get weekends off (could it be we weren't the audience they were after?). S is also for Sloane Square, the nearest Tube station, which, thanks to some stupendous forward planning on the part of London Underground, will be shut for engineering work next Saturday. And, most importantly for many, S is for Sell-off. The high point of the week, this takes place at 4pm on the final day, when a bell rings to signal the start of a buying frenzy as hitherto respectable middle-aged people fight over fuchsias and phormiums.

T is for Alan Titchmarsh, without whose televisual presence Chelsea would not seem complete. If you can't spot the real thing (look for the bossy television crew and the crowd of autograph-hunters), go to the David Austin Roses stand in the Great Pavilion, where a new rose named after him is being launched. It's pink and has a full, rounded shape. Just like its namesake. Bless.

U is for umbrellas, rain or shine. If it rains during Chelsea week, it is the kind of downpour that soaks through a Barbour and Hunter wellies before you can say "country attire". If there is sunshine, it's the sort that puts the St John's Ambulance teams on stand-by for heat stroke. Don't blame global warming - as long ago as 1928, a freak hailstorm blocked the drains, causing extensive flooding. Whatever the weather, people will be moaning about it. Gardeners are always whingeing about something.

V is for vegetables, a strong theme at Chelsea this year. Apart from Monsieur Blanc and the HDRA, award-winning herb specialist Jekka McVicar will be trying to encourage people to ditch the supermarket salad bag and grow her own mixes of salad leaves which are specially selected to be suitable for small gardens and containers. Veg of a more traditional kind - the varieties are all from a 1939 catalogue - will be growing on the Chelsea Pensioners' Garden, a nostalgic view of Britain in 1945 designed by Julian Dowle to recreate a soldier's dream of home. Which leads us on to...

W for war (and peace). The Imperial War Museum is celebrating the 60th anniversary of the end of the Second World War with a Commemorative Peace Garden designed by Sir Terence Conran. (Sir Terence designed a Dig for Victory garden for the museum at Chelsea in 1995 and caused a ripple of consternation by hanging a pair of bloomers on a washing line strung across it. Oh, I say!) W also stands for wildlife, another strong theme this year, particularly in the Wildlife Trusts Lush Garden, which demonstrates how to provide habitats for different creatures in your backyard.

X stands for cross, as in hybrid, and you'll see plenty of these in the Great Pavilion, where the nurseries will be showing off their new varieties. Bigger flowers, brighter colours, better scent: this is genetic modification at its most acceptable.

Y is for yuccas, those spiky stalwarts of the contemporary urban space, which are featured by Joe McHugh in his City Garden alongside agaves and aloes.

Z is for Zantedeschia aethiopica - the calla lily, or arum lily, as it is more commonly known - which is illustrated on the cover of the show catalogue. British gardeners are divided into those who hate Latin names and think those who use them are showing off, and those who love them because they, er, like showing off. So, that's Zan-ti-DESK-ya ee-thee-OP-ika. ...

For more information about opening times, tickets and the Royal Horticultural Society, go to www.rhs.org.uk. Tickets must be purchased in advance. Television coverage starts tomorrow on BBC1 with an hour-long special presented by Alan Titchmarsh and Diarmuid Gavin at 7pm. For full details of daily coverage, see The Information