The Chelsea Flower Show, the 100th, opens next week and this is an anxious weekend for the makers of the show gardens. Will a sudden frost murder tender plants hauled prematurely from their beds? Will an unexpected wind tear new leaves from trees uprooted from their comfortable nurseries and brought to stay for a razzmatazz week in town? Will the sponsor's money cover bills which by now may be reaching monumental proportions? Some of the big gardens will have cost more than a quarter of a million pounds to install.
This season has been exceptionally difficult because, as all gardeners know, in the grim cold days of April, nothing wanted to grow. For weeks at the Crocus nursery in Windlesham staff have been hauling plants into polytunnels equipped with special grow lights hoping to lure them into Chelsea mode.
Crocus is building the garden that the brilliant designer Christopher Bradley-Hole is bringing to Chelsea this year. The dark cubes of yew that provide strong structural elements in his design have been standing around on the grass at the nursery like pieces of a crossword puzzle. Now the puzzle has been completed and I'm predicting yet another gold for the designer. And for the nursery.
The cubes, each 80cm square, dictate how the interlocking grid of the garden had to be laid out. Bradley-Hole is a perfectionist. Everything is measured down to the last millimetre. Seen from above, the garden would look like a Mondrian painting, divided into squares and rectangles with blocks of yew, box and hornbeam, concealing and revealing narrow pools. Lapping round the rectilinear forms is a rich, stylised meadow, the prevailing greens lit up by flashes of red from Rosa moyesii and single red peonies. Under the beautiful single-stem hazels (we never usually see them grown this way) are sheets of lily-of-the-valley, dark-leaved Euphorbia robbiae and woodruff.
For many years, Japan has been a source of inspiration for Bradley-Hole (the Japanese architect, Tadao Ando is a particular hero). His initial idea for Chelsea this year grew out of a visit to the 15th-century abstract minimalist garden of Ryoan-ji in Kyoto, with its islands of rock rising from rippled seas of raked gravel. In his show garden, the rocks have become blocks of evergreen, the sea is translated into the flowing, blowing billows of sedge and moor grass.
Except that it's not as simple as that. The Bradley-Hole garden is in no way trying to be a Japanese garden. The Japanese vision has been fused with an idea of the English landscape, again, as if seen from above. But the shapes have been transposed. The blocks of evergreen represent the rectilinear shapes of our field system, with the more fluid plantings of perennials standing in for the remnants of woodland that, even in our overcrowded island, still wander between areas of more intensively cultivated land.
This will be the seventh garden that Bradley-Hole has brought to Chelsea and I've never seen one that wasn't elegant, calm, rich and superbly executed. All have provided what we need from our gardens – a retreat, a series of private spaces, with scent, the sound of water, and tactile pleasures. In this year's, you can imagine strolling quietly through his colonnade of good green oak, or slinging a hammock in the shade of his three hazel trees, shaped – so subtly you'd never notice – to suggest the sculpting of a prevailing wind.
His designs are always uncompromising, always modern, and the attention to detail he minds about doesn't come cheap. But no one who saw it has ever forgotten the first major show garden he brought to Chelsea. It was 1997 and nothing like it had ever been seen before. For years the show gardens had been drifting on automatic pilot showing nothing more demanding than herbaceous borders and waterfalls. Suddenly, boom! The gears shifted. Design with a capital D arrived and nothing was ever the same again.
But I remember an earlier appearance, in 1994, when, as the winner of a competition set by the newly launched magazine, Gardens Illustrated (and on a budget that f made a shoestring seem a luxury), Bradley-Hole, working then as an architect, built a plant hunters' garden using materials that had never before been seen on the Chelsea show ground: steel hawsers, canvas, the clean, elegant lines of a sailing ship translated into garden design. I was Associate Editor of the magazine at the time and we were high as kites with the excitement of it all.
I was with Christopher Bradley-Hole at the Crocus nursery a few weeks ago, looking at the mock-up of the green-oak colonnade that runs round two sides of this year's show garden. Watching the obsessive re-specifying of dimensions, materials, finish, you can understand how easy it could be for a designer to drown in the sub-plots of a show garden and lose sight of the initial vision. "You've got to hang on to that moment when you first got your big idea. It's really important because at that stage, you're not judgmental," he says.
We walk round the nursery with Peter Clay, co-founder of Crocus, looking at the plants destined for the show. "They're incredibly low," says Bradley-Hole as we gaze at several rows of Astrantia major 'Claret'. "That's a key plant." "Look, they're being individually hand-fed," replies Clay, soothingly. But it does seem that Chelsea is a year's worth of major worries for the designer of a show garden. Will those astrantias decide to grow? Will the extra charring he's ordered on the oak boards give them the texture he's looking for? Where's the pay-off? "Why do you do it?" I ask.
"It's the one opportunity you have to bring an abstract idea to a level of finish that is rather rare. The designer gets pushed. You can realise your vision – completely frozen in time. There's absolutely nothing like it," he says. And then he disappears to make yet another adjustment to a line of flints running along the back wall of the colonnade.
The Chelsea Flower Show is celebrating its centenary this year. Television coverage starts this weekend and continues throughout the week of the show with a lunchtime programme on BBC1 and an evening slot on BBC2
The Chelsea Fringe Festival
Set up last year by Tim Richardson, the Chelsea Fringe is this year offering 160 events mostly in and around London, from today until 9 June. At the heart of it is the idea that we should re-think our ideas on what gardens are for. And there's a new focus, with some extraordinary 'plantings' at Battersea Power Station, where there'll be multiple installations, sculptures, interactive shows, as well as food markets. Other events to look out for include:
*A new Edible Bus Stop, opening today outside Lambeth Hospital on Landor Rd SW9, to delight passengers waiting for the 322 bus. The ultimate aim is to have similarly productive stops along the whole of the 322's route.
*A Gnome Invasion in Ockendon Rd N1, where residents have been invited to paint garden gnomes (banned from the main Chelsea show) to sit alongside the trees that add so much to the Islington landscape.
*Edible High Road: last year's event was staged in Chiswick. This year the action moves to Salusbury Rd, Queen's Park NW6, where for the next six weeks, fruit trees will blossom in tubs all the way down the road. Afterwards they'll be planted out permanently in school and community gardens.
*Guide yourself on a walk through London's historic parks and gardens with a free Fringe e-book, available to download from today.
*Today an orchard of people will be 'planted' at Battersea Power Station by the Pop-up Foundation, who will share their ideas on moving to a more environmentally-sustainable future.
*Beat the traffic tomorrow at Gibraltar Terrace, Chatham, Kent to cheer on a community project which aims to green up the fume-laden A2 with a massed series of pots and window boxes.
*Today the British design company, Squint, is putting on a museum of terrariums at their HQ in 1 North Terrace SW3. Miniature enclosed worlds for those who like their plants kept in hand.