The series is based on a book of lively letters exchanged across the Atlantic by the pair, described by the publisher as "eccentric gourmet gardeners", like some weird hybrid of Keith Floyd and Vita Sackville-West. Gardeners they are, gourmets perhaps, but it's too easy to mistake enthusiasm for eccentricity.
Roger, an expert plantsman, may have an odd way with a ham, yet his achievement in reviving the community garden in London's Eccleston Square is significant. Leslie, a food and gardening writer, suffers from a bung-in-everything approach to cooking (eg blueberry peach upside-down cake with raspberry cream) but in growing high-class produce in Maine, frozen over for much of the year, she shows herself an accomplished cultivator.
A former advertising copy-writer and photographer, Roger became a successful gardening author with his first book about wild flowers. His other areas of expertise include roses and mushrooms, and it was mushrooms that brought bim into contact with Leslie.
"We met at the New England Foray in New Hampshire," he told me. "All the mushroom societies in the north-eastern United States gang together every year for a mushroom hunt and in 1989 they invited me along. Leslie was there and we got chatting. Two days later the New York Times ran a big article about her garden in Maine and I wrote to her."
That letter is the first in the book, published two-and-a-half years ago and now reissued as a paperback, with extra correspondence added, to tie in with the television series.
"It was terrific chatting you up at the mushroom bash," he wrote merrily. "There are lots of other things I wanted to say but never got round to." He made up for it in a long description of the Eccleston Square garden, outlining his hopes and fears for its future.
Within days Leslie had responded in kind with a description of her Maine acres. Her persona, as revealed in the letters and on screen, is a daunting combination of earth mother and flower child, marvelling at nature's bounteous profusion and sometimes wanting to eat it all up at once.
As their correspondence progressed, it was not long before they were exchanging weeds, sketches, pressed flowers, recipes and even closer intimacies ("I'm horny when I'm happy"
- Leslie). There are times when the book's mutually congratulatory tone comes cloyingly close to self-parody, and once or twice the television programmes fall into the same trap.
There is a limit to how often you want to be told about the superlative flavour of Leslie's brandy-wine tomatoes or the unalloyed beauty of Roger's camellias. You get to wish that, just once, she would pluck up the courage to tell him that camellias are naff, and that he would counter with: "Your recipe for panfried shad with rhubarb compote made me throw up."
He insists that the idea of publishing the letters came only after he had amassed a substantial pile of them. Given their length and polished feel, sceptics will find it hard to believe that no thought of publication had occurred to these two professional writers before they put pens and, more usually, word processors to paper. There is an obvious similarity with Helene Hanff's popular 84 Charing Cross Road, recording her cute correspondence with a London bookseller - although Roger says he has not readit.
It is curious, too, that the exchange ended abruptly as soon as the first edition of the book was published, to be resumed only when the television series was mooted. But let's not get too literal about this: even if we are required to suspend disbelief on the question of its genesis, the charm and verve of the series wins us over.
The story of the Eccleston Square garden is itself an inspiriting one. It is a private, locked three-acre square near Victoria Station, with access limited for the most part to the residents of the surrounding houses, built by Thomas Cubitt in the 1830s over what used to be fertile smallholdings.
The garden is run today by a committee of residents. Fifteen years ago, soon after Roger and his wife Nicky moved there, it was in a bad way and the committee, learning that they had an expert in their midst, asked Roger to take it in hand.
He acquired lorry-loads of spent hops from Young's brewery across the river in Wandsworth, and used them to add heart to the soil's texture.
Then he started tearing out those plants and shrubs that were past their best, which meant most of them, and putting in quantities of new material designed to give colour all year. Some of the scores of pink and white camellias are in flower already. In spring these will be followed by the predominantly blue ceanothus - the garden has more than 50 varieties - then an extraordinary array of roses.
The basic shape of the garden has been maintained, with the paths around it as Cubitt designed them. Within that framework Roger has created a number of "secret gardens", shady plantations with mini-paths running through them. These are popular with children, who also enjoy the play equipment he installed.
Some keen residents have taken responsibility for specific parts of the garden but Roger is the mastermind, with one full-time and one part-time gardener to help. In summer the square is well used for picnics, parties and barbecues, though music and marquees are banned.
Soon after Roger began his correspondence with Leslie, he had alarming news for her. The square's freeholders were planning to build a car park beneath it, with all the disturbance and pollution that that implied. The residents mounted a campaign againstit and Leslie rallied to the ranks by unearthing a protest song, Joni Mitchell's "Big Yellow Taxi", which includes the line: "They paved paradise and put up a parking lot."
In the end, nobody had to sing it because the council refused planning permission. By chance, when the TV series was being filmed, an almost parallel threat emerged at nearby St. George's Square, so the earlier agitation could be recalled for viewers. That proposed development was scotched, too.
The six programmes are chronological. Tonight's deals with the deep midwinter, when Roger is baking his ham in the leaf pile while Leslie, her Maine garden snowed under as usual, sends him some of last year's tomato seeds between sessions on the ski slopes. In the concertina time-scale of television, the abundance of autumn will be reached by early March.
Leslie sums up the philosophy of the enterprise in one of her letters: "The big problems - poverty, war, the whole caboodle - all boil down in the end to one basic question: who gets to eat good food, breathe clean air and smell a few flowers in peace?" Enjoy...and pass the rhubarb compote.
`The 3000-Mile Garden' begins its six-week run tonight on Channel 4 at 8pm, with repeats on Mondays at 4pm. The revised edition of the book is published by Pan at £6.99Reuse content