Did someone die just then, or what?: 'Griefwork' - James Hamilton-Paterson: Jonathan Cape, 14.99 pounds

IT SEEMS odd, given the fierce British enthusiasm for gardening, that there should be so few green-fingered heroes in our literature. Modern times, in particular, have proved to be stony soil. There is Lady Chatterley's lover, but botanical pursuits are hardly the only thing on his mind. So it is refreshing to see at the centre of James Hamilton-Paterson's absorbing new novel a man with dirt under his tobacco-stained fingernails.

Leon is the head of an iron-and-glass palm house in a nameless European city. He is a genius with plants: he only has to murmur sweet nothings and, well, it's every time a coconut. He once created a lively stand of bamboo just by planting a walking stick; and he is on second-name terms (Acalypha hispida, Brownea grandiceps, Tamarindus Indica) with all the exotic fronds and orchids in his warm glass home.

This hothouse is a remarkable place: 'It was as if once, unknown ages ago, a tropical forest had covered this part of the earth until one day people had noticed it retreating and had clapped a greenhouse over a remaining tentacle like a tumbler over a butterfly.' But beneath his supernatural sensitivity to the play of moisture and shade on broad leaves, Leon is mourning a lost love. He may be able to read palms, but he can't tell the future, and he does not see the forces that are converging on his little glazed paradise.

As a boy on the windswept North Sea coast, he fell for an Asian girl called Cou Min. Ever since, his life has been a sort of tribute: indeed the entire palm house is a monument to her memory - an artificial tropic, full of echoes of transplanting and uprooting, and with snow on the roof. Leon is a rare plant himself: his weak lungs flourish only in a steamy atmosphere, and he is too fond of his seedlings and tubers to worry about life outside - the Second World War, for instance. 'Like a mongrel or a holy man,' we are told, 'he transcended the usual social distinctions.'

He inhabits, in other words, a marvellous world. Hamilton-Paterson is attentive to the dense poetry of stalk and bud, and his prose, when he stays close to natural phenomena, is both lush and exact. In just one of many likeable improvisations, he describes how the neighbouring zoo has been ransacked by the occupying army: 'They found very little. Exotic menus had long since passed through the ovens of the officers' mess and indeed the officers themselves: cassowary Kiev, giraffe steaks, panda pie, llama sausage. Three elephants, two hippos and a white rhino had provided hundreds of troops with tough but nourishing meals, while to the highest ranking officers had gone one bonne-bouche after another: koala tongue pate, lion tamarin in raisin and kummel sauce, buttered marmoset.'

It is a pity that the author was not happy to let the novel be what it feels like at moments such as this: a wistful yet vigorous parable about nature and decay, given ballast by a merry weight of organic matter. But Hamilton-Paterson has more pretentious fish to fry. As the title implies, this is a story about sorrow, and the idea is spelt out in full: 'Mightn't grief quite efficiently frame the structure of an entire life?' The answer seems obvious: yeah, sure. But the manner of Leon's grieving takes a curious form.

He is forever brooding on a bundle of events and impressions from childhood: a whirling lighthouse beam that swats his bedroom at night, the scent of Cou Min's knee, a glimpse of golden sunlight on the spar of a sailing ship. Fresh incarnations of these images give the book an undeniable symbolic coherence, but it is all rather frosty and calculated.

Hamilton-Paterson is a poet, and sometimes he is fatally decorous. Leon's mother, for instance, is killed in a flash of pretty but purely symbolic ecstasy: 'As the window struck the top a single diamond pane flew from its mounting and twirled languidly down in a bending trajectory. This fluttering glass blade took Christina at the base of the neck and killed her where she stood.' This is lyrical, but . . . did someone die just then, or what? At its worst, this fondness for lofty poetic language (the book is full of curlicues, crenellations, and so on) suggests little more than that we are, in case we haven't realised it yet, in the presence of an aesthete.

Still, Hamilton-Paterson conjures some dainty effects. Leon is presented as wind-driven and he can speak plant language. When Prince Charles does this, everyone jeers, yet in Leon it seems an accomplishment of almost Franciscan devotion. The novel's most striking stylistic adventure is a series of speeches by the trees in Leon's hothouse. There is a philosophical debate going on here between the smaller ferns, which resent the 'master-race complex' of the giant palms. And a plant romance mirrors the longings of Leon for Cou Min. The mighty tamarind casts lustful glances at the hemlock tree growing in its shade.

But the Latin name for hemlock is Conium - a easy anagram. What on earth is Hamilton-Paterson trying to suggest? That Cou Min has poisoned a man's life? It wasn't her fault that Leon never recovered from the shock of picking up her handkerchief. There is something odd and, to be honest, not that interesting about all this. Leon keeps making up to people who remind him of Cou Min. He flirts with a new Asian princess who visits his garden at nights and offers him a job (she wants to create an inverted hothouse in the tropics, a fridge full of crocuses and daffodils). And the rest of the time he doggedly penetrates, like his beloved thorny Acacia Farnesiana, a gypsy boy he has rescued and installed in the boiler room.

Cou Min, by the way, is also the spice, cumin, and it won't have escaped Hamilton-Paterson's attention that cumin is what the dictionaries call carminative - a medication for expelling wind. What a shame he has made so free with it: Griefwork is by any standards a work of unusual intensity, and Hamilton-Paterson is the genuine article, a writer pursuing his own distinctive course away from the hullabaloo surrounding lesser lights. But this novel might have been even finer had the wind been allowed to fill its canvas. The idea of Leon as an unworldly plant genius is much more moving than the notion of him as an unhappy lover with a 'sweet ailment'.

Hamilton-Paterson's previous book, Seven Tenths, was a thrilling and serious hymn to the sea; and was so well-wrought as to suggest a writer too intelligent and canny to let a good story run away with him. Here, he tosses up magic on every page, but in seeking to make it explicable he chucks anchors overboard with bewildering haste. If only he had let Leon haul the spinnaker up and see how far the wind would carry him. But instead he trims and tacks, and veers this way and that; and though he is much too accomplished to capsize, the scrape of someone tangled in the rigging is never far away.