Blurred boundaries

No gardener is an island, although some have tried to be. It took Richie Sowa six-and-a-half years to built his floating temple to self-sufficiency in a lagoon near Puerto Aventuras, on the Mexican Caribbean. Living, for the first year, in a tent, he collected old fishermen’s nets and filled them with 250,000 used plastic soft-drink bottles, to form a tennis-court-sized base for what would become Spiral Island.

On this buoyant foundation, Sowa, a former carpenter and now artist and self-styled ecological pioneer, constructed a frame from bamboo and discarded plywood to contain tonnes of sparkling white beach sand. Upon this layer, in turn, he built a two-story house with rainwater shower, composting toilet and solar oven. And he planted a garden: of sprawling mangrove shrubs, passion fruit vines, sea grape bushes, banana plants and papaya, lime and coconut trees.

Sowa meant Spiral Island to be not only a place for him to live – along with his eight cats and a dog – but also a kind of floating billboard for parsimonious living in the face of an increasingly imperilled nature. “I envisage thousands, even millions, of floating eco-islands around the world,” he says. “They could clean up unsightly trash, provide sustainable land for a booming population, filter dirty water through their plant roots and ease the burden on a suffering planet by encouraging people to use energy from the sun, wind and waves.”

Sadly, the planet, in the form of hurricane Emily in 2005, spelled the end of Spiral Island. Sowa’s unlikely mobile home weathered the storm largely intact, thanks in part to the vigorous mangroves, whose roots had interwoven with the soda-pop-bottle base, but it was, nonetheless, irretrievably beached. Yet his idiosyncratic project has won him modest fame – including, at one point, the attention of the US television programme Ripley’s Believe It or Not – and his hopes remain afloat. He has begun work on a bigger, better “eco-ark”, this time with several investors on board.

Islands are rarely the idylls of the imagination. They are more often exposed places with peculiar climates, breeding equally strange fruits. On Spiral Island, Sowa noticed that his mangroves grew twice as fast as their cousins only a few metres away on the shore; he put it down to the constant waterline on his craft as it rose and sank with the tide.

I think, similarly, of the species flourishing on the Scilly Isles. In their subtropical climate, the gift of the Gulf Stream swirling about the south coast of England, the many ardent Scillonian gardeners grow dainty South African bird of paradise plants and stubby aloes and protea; agave cacti reach a freakish, nightmarish size; and it is somehow fitting that the hallucinogenic datura weed, banned on the mainland, hangs on to tempt the island’s restless teenagers. Some of the gardens I saw on a recent visit came right down to the sea, which would inundate their lower reaches when it was in particularly ferocious mood.

Such horticultural isolation can mirror a human one. Modern Scilly is largely the fruit of the benign autocratic rule of one Augustus Smith, the 19th century industrialist who leased the islands in their entirety and sought to extricate their inhabitants from the poverty and criminality in which neglect by the rest of England had left them.

I think also of the even more extreme case of Sark, the smallest of the Channel Islands, which retains one of the last feudal systems in the world. You could easily forget the invention of the car on Sark; automobiles are banned and many islanders get around by horse and cart. The fiefdom, all two square miles of it, even developed its own language, Sercquiais.

At the apex of Sark government is the Seigneur, within whose innermost domain of La Seigneurie lies a walled garden that provides a compact metaphor for the singularity of island life, plant and human, in general. At 350ft above sea level, the grounds of the 17th century estate are, like much of the island, whipped by wind, against which the garden walls offer some protection.

That boundary, chief gardener Judith Windle tells me, forms a microclimate within which all sorts of improbable species sprout. “You can walk into the garden and it will feel 10 times hotter here than anywhere else,” she says. “The heat bounces off the walls. We try everything; bottlebrush, tea tree, canna lillies and other Australian plants grow in profusion. The Madeiran species grow well; so do some of the tenderest perennials and annuals.”

“We’re very lucky, being enclosed. But the wind can still do a lot of damage; it comes through the gate and can swipe anything away.”

Other island gardeners make a virtue of such conditions. On Nantucket, off Massachusetts, Jenne Atherton, a resident and professional gardener, tells me that the wind – swerving from a south-easterly in summer to a north-easterly in winter – makes it difficult to grow trees or anything tall by the ocean. She sticks to hardy native shrubs and grasses in seaside gardens, laid out in a loose, natural-looking style.

In landscaping his stretch of the Brazilian Peninsula de Marau (which is cut off, island-like, from the mainland 90 per cent of the time), Bob Beadle says he was much influenced by the legendary garden designer Roberto Burle Marx, whom his wife knew towards the end of his life. Marx’s great innovation was the way he incorporated local wild vegetation to blur the boundaries between nature and design.

In like manner, Beadle and his wife have over the past three years transformed their beachfront property from a vine-choked patch to an intriguing landscape merging rare Atlantic rainforest plants with gaudy orchids, giant, 2-metre-tall bromeliads, hardy sandspit survivors and a 100-year-old coconut plantation.

All sorts of odd species thrive on islands.

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