On 18.8 acres of parched, wind-swept land once devoid of everything except hardy invasive plants, W.S. Merwin has created what may well be his magnum opus. The celebrated poet, now 90, refers to the lush forest that surrounds his modest off-the-grid home in Haiku, Maui, simply as “the garden.” In reality, it is nothing short of a miracle.

Merwin chronicled the transformation in an essay, “The House and Garden: The Emergence of a Dream,” which appeared in the Kenyon Review in fall 2010. “The land had been pronounced wasteland, ruined beyond agricultural use, after little more than a century of abusive exploitation,” he wrote. “I had long dreamed of having a chance, one day, to try to restore a bit of the earth’s surface that had been abused by human ‘improvement.’”

In the 1840s, ambitious entrepreneurs began clearing native trees and shrubs in the area to provide pastureland for cattle and fields to grow sugar cane and pineapple. Those businesses ultimately failed, and the speculators moved away, leaving eroded soil lacking in nutrients. Parcels still classified as “agricultural land” were put on the market in the 1970s.

Merwin bought 3 acres in 1977, built a house and set to work, hoping to restore a few acres of the “pure Hawaiian rainforest” that had once thrived there. Unfortunately, koa, ohia and other native species that he, wife Paula and their friends planted didn’t survive because the earth was no longer fertile.

To Merwin’s delight, however, Hawaiian palms, with their dense root system, did well in land he had enriched with manure and seaweed. “I began corresponding with palm growers and botanical gardeners in other parts of the tropics, and learned, from reading, how to grow palms from seed,” he wrote. “It was an exciting time, and the palms I managed to grow, and the emerging garden, added to our attachment to our life here.”

He and Paula purchased an additional 15.8 acres of adjoining land in 1986 and continued to plant. Today, about 2,740 palms representing more than 400 species thrive in Merwin’s garden — one of the largest and most diverse palm collections in the world. Each palm has been taxonomically identified, botanically tagged and recorded in an online database.

Interspersed among the palms in the wondrous disarray are hundreds of other kinds of plants and trees, most of them tropicals, such as orchids, mango, banana, hala (pandanus) and ginger.

Paula died in March, but he still lives in the house they shared, in the midst of the forest that he brought back to life.

The nonprofit Merwin Conservancy was founded in 2010 to preserve the garden and the poet’s home in perpetuity and to fulfill his vision to establish the area as a retreat for writers and a resource for environmental advocacy and community education. At least once a month on Open Garden Day, the organization invites the public on a two-hour hike through the property.

Focal points, of course, are the amazing palms. To discourage predators, Salacca vermicularis displays sharp thorns on its stalks. While most of its cousins require a balmy clime, Trachycarpus fortunei can tolerate temperatures as low as minus 27 degrees. Nicknamed the “walking palm,” Socratea exorrhiza grows new stiltlike roots on one side while roots on the other side die. This enables the tree to move away from obstacles and into areas with more sunlight. Notably, 15 of the 19 palm species are native to Hawaii.

Readings of Merwin’s poetry — which started as scribbles on napkins, scrap paper and the envelopes of opened mail — are woven into the experience.

Merwin has published more than 50 books of poetry, translation and prose during a career spanning 65 years. In addition to his appointment as U.S. Poet Laureate in 2010, he is the recipient of numerous literary accolades, including Pulitzer Prizes in 1971 and 2009 and the National Book Award for Poetry in 2005.

He wrote some of his best poems in the garden, during breaks from planting, shoveling compost and watering seedlings with buckets of dishwater that he hand-carried from his house.

The work continues (just 10 acres of the property have been planted thus far), and it is hoped that during their visit guests will be inspired to become “gardeners” themselves.

Matthew Schwartz is the Merwins’ son and president of the Merwin Conservancy’s board of directors. As part of the poet’s 90th-birthday tribute held Sept. 29 at the Maui Arts & Cultural Center, he shared his parents’ wish for the garden: “To help us all understand that wherever and however we live, we too can find our own connections between art and nature, to plant our own trees in our own way.”

Cheryl Chee Tsutsumi is a Honolulu-based freelance writer whose travel features for the Star-Advertiser have won several Society of American Travel Writers awards.