No nation is more besotted with gardens than us, so it was inevitable that Tate Britain would get around to mounting a major show called "Art of the Garden". Images of horticultural prowess are legion in British painting. And some artists have taken this love affair to an ambitious extreme by turning their gardens into highly considered artworks. As such, I went along to the Tate expecting an orgy of flourishing flowers and foliage, celebrating an infatuation with fecundity.
Mercifully, however, the exhibition is far more than a pictorial version of the Chelsea Flower Show. The opening pair of paintings, in which John Constable pays tribute to his father's gardens in Suffolk, may seem straightforward enough. But the shadow spreading over the lawn, along with a darkening cloud above the horizon, alert us to a more elegiac mood. Even as he defines the richness of this parental haven, Constable mourns the loss of his mother, Ann. She had died that year, 1815, defeated by exertions in the flower garden. Her fever, according to Constable's brother, had been brought on "by the cold, which was very severe, & stooping to weed".
Thus, right from the outset, we realise that gardening can be a source of mortal danger as well as delight. And the garden itself turns out to be a place where complex and conflicting emotions thrive. When Spencer Gore looked down from his flat in Camden Town on the eve of the Great War, he filled much of his canvas with the writhing forms of an immense fig tree in the garden below. A woman stands alone beneath its branches. She may be Gore's young wife, so the painting could be a simple reflection of his love for her as well as his willingness to learn from Paul Gauguin and Vincent Van Gogh. But she appears strangely remote and forlorn, confined by the surrounding houses.
Soon enough, we find ourselves confronting the impact of war. In 1940, Harry Bush produced a painstaking picture of a deep crater gouged by a Luftwaffe bomb in the back garden of his house at Merton, Surrey. All around, windows and roofs have been shattered by the blast. But Bush catches the unnerving air of stillness in the raid's aftermath, and the stoicism of two minuscule figures conversing amid the desolation. Later in the war, Adrian Allinson painted plucky members of the Auxiliary Fire Service creating allotments in a "dig for victory" at the heart of St James's Square, in central London.
Even when the show moves on to the theme of the secret garden, the notion of an idyllic retreat soon finds itself threatened by menace. Samuel Palmer's watercolour In a Shoreham Garden (1829) is ecstatic enough, as an apple tree freighted with plump, burgeoning blossoms seems on the verge of exploding into the sky. But Richard Dadd's Portrait of a Young Man (1853) introduces a more tense and melancholy feeling. Dressed in funereal black, the sitter may be a doctor called William Hood, who helped "Mad" Dadd cope with mental instability while incarcerated in an asylum. The young man looks sombre, while the sunlit garden stretching behind his bench is seen as an unattainable place, where the frustrated Dadd must have longed to roam at will.
In Mat Collishaw's large colour print Who Killed Cock Robin? (1997), three little children gravely offer a bouquet to the dead bird laid out before them. The children seem oddly shrunken in comparison with the colossal size of the petals and plants surging above their heads. Nature's fertility here seems out of control, and quite capable of dominating humanity in a science-fiction nightmare. At first glance, John Singer Sargent's much-loved canvas Carnation, Lily, Lily, Rose looks like a beguiling tribute to the magic of an exquisite garden where two girls stand enchanted as dusk advances. Sargent certainly made every effort to arrive at a convincing depiction, restricting himself to working only for the brief period each day when the light was precisely as he wished. But he confessed that the floral magnificence in his painting was a wholly artificial device. The "rose trees" were in reality concocted from black weeds, with tied-on flowers from a friend's hat.
Like Sargent, the film-maker Derek Jarman was able to create a sense of wonder from the most unlikely starting point. Down at Dungeness, on a bleak coastal location in Kent dominated by the glum hulk of a nuclear power station, the defiant Jarman managed to grow a wonderfully idiosyncratic garden. Howard Sooley's photographs, taken around 1990, testify to the blooms Jarman nurtured in his wilderness. And the close-up shots reveal how eloquently he made use of the most lowly found objects: a rusting spanner, lodged in a cleft stick, takes on a surprising sculptural power in this inventive, rule-breaking context.
Barbara Hepworth also knew how to display sculpture in a garden of her own devising. Her bronze Corymb (1959), inspired by the forms of a flat-topped flower cluster, reminds us of the fusion she achieved at the centre of St Ives in a place where art and horticulture sustain each other at every turn. And Little Sparta, the outstanding Scottish garden planned and nurtured to this day by Ian Hamilton Finlay, is granted a special installation with recorded flute accompaniment. His 11 black-and-white photographs, each in halves mounted on Perspex, stress the profound influence of Poussin. Full of musical references, they show how Finlay encourages us to meditate on history as we explore his remote and irresistible retreat.
When William Nicholson was commissioned to paint Gertrude Jekyll's portrait in 1920, she refused, maintaining that "ugly people had better not be painted". But Nicholson succeeded in conveying a great deal of her resolute character by producing a small, succinct study of Miss Jekyll's Gardening Boots. They sit, paying unmistakable homage to Van Gogh's painting of his own battered boots.
Cedric Morris, the teacher who nurtured a remarkable garden in Suffolk, admitted that flowers fascinated him because of their "grimness, ruthlessness, lust and arrogance". Hence the macabre mood of his grand yet weird and unsettling canvas Iris Seedlings (1943). Marc Quinn also catches this uncanny quality in a large working drawing for a frozen flower garden. As many as 75 species are represented here, ready for immortality in the enormous steel refrigeration tank that Quinn devised for their eternal protection. Paradise is evoked, but the eeriness of Quinn's frozen petals cannot be ignored. They anticipate a disconcerting future where artifice has triumphed over nature.
"Art of the Garden" is at Tate Britain, Millbank, London SW1 (020 7887 8008) until 30 August