Henry Moore in Kew Gardens

Nature is a tricky partner when it comes to sculpture. For thousands of years it took the lead, with artists striving to outdo or merely ponder on its sheer abundance. Today, artists who seem too happy to ingest natural forms and textures in their work risk being dismissed as retrograde sentimentalists. This contemporary distrust of "landscape" as a source of ideas is especially fraught in the UK, where our landscape tradition has been particularly hard to dislodge. Instead, the self has taken over as the territory of choice, providing artists with material they can easily control.

For the last two decades of his life, Henry Moore (1898-1986) upset the avant-garde simply because he wouldn't let go of nature: "As well as landscape views and cloud formations," he said in 1973, "I find that all natural forms are a source of unending interest – tree trunks, the growth of branches from the trunk, each finding its individual air space, the texture and variety of grasses, the shape of shells, of pebbles, etc. The whole of nature is an endless demonstration of shape and form; it always surprises me when artists try and escape from this."

Visitors to the Royal Botanic Gardens at Kew, where 28 large-scale works by Moore are on display from this weekend, might well agree. There, dotted around a landscape setting in which all the textures and colours the natural world has to offer are at hand, stands a testament to a busy life led with nature and man in mind. Curated by David Mitchinson, of the Henry Moore Foundation, the exhibition is the largest-scale display of Moore's sculptures in London for a generation. It is not so much a display of art as a reminder of the rewards that come from coopting the natural world as a creative ally.

"Natural" must of course be taken with a pinch of salt, since Kew is really an elegant retirement home for show-off plants, herbaceous refugees and near-extinct freaks, designed by successive gardeners and scientists. Nonetheless, for most people it is an Eden, except for the lumpen metal planes that scream their angry way to Heathrow. Below stand Moore's lumps of metal, some rearing into the sky like Jurassic knobble-boned throwbacks inside a lush green swamp, except that neat Kew, a World Heritage site, needs a hundred years of climate change to complete this picture.

For me, the installation reveals the underlying formality of Kew's setting, with pieces such as Moore's Draped Reclining Mother and Baby and his Large Standing Figure: Knife Edge working beautifully with the quietly regal avenue leading from the Orangery to the Palm House. Other pieces, such as his Large Reclining Figure, straddling the lawn near the pond where it is seen against the Palm House, make a bigger show of independence.

The inspiration for this striking white sculpture came from a lead maquette only 33cms (13in) long that Moore made in 1938, although it wasn't until 1983 that the artist developed it into this full-size sculpture. Its strongly biomorphic forms suggest the influence of the Surrealists, with its dreamy distortions and shifting parameters. Moore photographed the maquette against the Kent skyline in the 1930s so as to make it appear colossal, suggesting that it was always his intention to produce a work on this scale. The piece was made in white fibreglass to make it more transportable.

Some avant-garde critics were frustrated that many of Moore's pieces were not made for specific sites but were instead designed to be independent. They felt that he failed to draw sufficiently on the site-specific investigative strategies used by artists working in the Conceptual Art or Minimalist styles.

Moore's large works, such as Large Upright Internal/External Form, made in 1981-82, and the biggest vertical piece he ever made, can take Kew in its stride. It balances the expressiveness of its external and internal elements without losing the unstable energy of either. His sculpture is famed for its "invention" of interior space within the sculpted form. Positioned at Kew in a long vista towards the Pagoda, it gives a visual balance to one of the garden's best known landmarks.

Most of Moore's reclining figures – a sculptural form that he made his own – were conceived as two-dimensional works, designed to be viewed from either the back or front. Reclining Figure: Arch Leg (1969-70) upsets this convention and seems more three-dimensional. It can be approached from a variety of viewpoints, so you can't tell which is the front or the back. Mitchinson says that the key to guiding the visitor's approach to such works lies in shaping access to the sculpture by managing its relationship to the neighbouring buildings and other large-scale objects.

This process of discreet shepherding also allows for a greater focus on material texture. The exhibition in general brings together a wealth of surface treatments, from highly-polished areas to heavily textured, ridged surfaces, from the hygienic bright white of fibreglass to the earthy tones of red-brown, gold, black and serpentine green.

Perhaps the strangest works on show are the series of 12 Upright Motives, undertaken by Moore from 1954 onwards. They remain among the most enigmatic of all his works, and the public and many sculptors have found them hard to understand. They seem to be as much sculptural explorations of totemic form as a creative reference to the typical subjects of traditional anthropological study or the strangely fascinating artefacts found in ethnographic collections. Seen against the evolution of Moore's work, their writhing forms imply a struggle between figurative and abstract impulses, but one that was highly creative in its own right.

At Kew, they stand at various heights against the Princess of Wales Conservatory, almost a study of a crowd scene. As far back as 1951, Moore stated: "Sculpture is an art of the open air. Daylight, sunlight, is necessary to it, and for me its best setting and complement is nature. I would rather have a piece of my sculpture put in a landscape, almost any landscape, than in, or on, the most beautiful building I know."