We are deeply saddened to share the news of the passing of Seamus O’Brien, a beloved figure in the gardening and botanical community. Seamus O’Brien passed away suddenly on December 22, 2025, at the age of 55. He was one of Ireland’s best-known horticulturists, celebrated for his warmth, expertise, and transformative work in Irish gardens. In this tribute, we reflect on Seamus’s life, achievements, and lasting legacy in gardening, a legacy that closely aligns with our own mission in botany, biodiversity, and sustainable horticulture.
Reviving a Historic Garden at Kilmacurragh
Seamus O’Brien served as the head gardener at the National Botanic Gardens’ Kilmacurragh Estate in County Wicklow, a role he took up in 2006. When the historic Kilmacurragh gardens came under state care, they had fallen into neglect after years in private hands. Through vision and dedication, Seamus transformed the estate’s once-overgrown grounds, including its famed rhododendron walks, into a flourishing botanical haven open for public enjoyment. His stewardship helped turn Kilmacurragh into “one of the jewels in the crown of Irish gardens,” as colleagues fondly noted.
Earlier this month, Seamus welcomed news that the long-abandoned 17th-century Kilmacurragh House (around which the gardens are built) was finally set to be restored. He believed that rebuilding the manor and opening an additional 50 acres of restored parkland would return Kilmacurragh to the ranks of Ireland’s great estate gardens. This announcement reflected Seamus’s unwavering commitment to rejuvenating the estate’s heritage. In fact, he even spearheaded the revival of the 300-year-old wildflower hay meadows on the property. Using regenerative and sustainable gardening practices, he created what he fondly called a “little Noah’s Ark of wildflowers,” a thriving haven for pollinators, birds, and biodiversity in the gardens. Thanks to Seamus’s efforts, Kilmacurragh stands today not just as a beautiful landscape, but as a living example of restoration, conservation, and horticultural excellence.
A Passionate Plant Hunter and Author
Beyond his work in Wicklow, Seamus O’Brien was renowned as an intrepid plant hunter and an accomplished author. He received formal horticultural training at the National Botanic Gardens in Glasnevin and an international diploma from the Royal Botanic Gardens, Kew. In pursuit of botanical knowledge, Seamus traveled extensively around the world, from the Himalayas of Bhutan and Nepal to the forests of China, India, Myanmar, and beyond. His expeditions in search of rare plants echo the adventures of history’s great botanists, and he recorded these experiences in writing. Seamus authored two award-winning books, In the Footsteps of Augustine Henry and his Chinese Collectors and In the Footsteps of Joseph Dalton Hooker: A Sikkim Adventure, which recount historic plant-collecting journeys and his own travels in their footsteps. These works not only earned acclaim but also helped preserve important botanical history and inspire gardeners worldwide.
Seamus’s expertise and storytelling made him a sought-after lecturer internationally. He had a special talent for combining his love of travel, fieldwork, and plants in lively presentations. In recognition of his contributions, Seamus O’Brien was inducted as a member of the famed Explorers Club, a prestigious society of adventurers and scientists whose alumni include Everest conqueror Edmund Hillary and astronaut Buzz Aldrin. This honor underscores the high esteem in which he was held globally for his botanical exploration. Closer to home, Seamus was also a respected member of the Royal Horticultural Society’s Woody Plant Committee and served as a judge for RHS shows. In 2018, he was awarded the Royal Horticultural Society of Ireland’s Gold Medal of Honour for his distinguished service to horticulture in Ireland. And most recently, in 2022, Seamus won the Loder Rhododendron Cup, becoming only the second Irish person in the award’s 100-year history to receive that prestigious honor for rhododendron cultivation. Each of these accolades speaks to his extraordinary knowledge, passion, and impact in the field.
Champion of Biodiversity and Sustainable Gardening
Seamus O’Brien’s philosophy of gardening went hand-in-hand with respect for nature. He possessed vast knowledge of both native Irish plant species and exotic plants from around the world. Importantly, Seamus was a forward-thinking advocate for gardening in a changing climate and for the protection of the natural environment. Long before sustainable gardening became a buzzword, he was demonstrating how botanical gardens and home gardeners alike could adapt to climate challenges by cultivating resilient plant collections and conserving biodiversity. The thriving wildflower meadows he restored at Kilmacurragh, mentioned earlier, are a shining example of his commitment to ecological gardening, providing shelter and nourishment to countless pollinators and preserving genetic diversity in plant life.
Colleagues and visitors were continually inspired by Seamus’s infectious enthusiasm and deep well of knowledge. He had a gift for educating others with a warm, approachable style. Garden writer Jane Powers observed that it was “one of the wonders of Irish gardening” to watch Seamus grow into an internationally respected expert while always retaining his generous spirit and sense of humor. Indeed, those who knew him often note how generously he shared advice, historical anecdotes, and horticultural expertise, always with a smile. Seamus understood that gardening is not just about plants, but about people and passion. By mentoring young horticulturists, giving public talks, and writing accessible books, he nurtured a love of plants in everyone around him. His approach aligns strongly with our organization’s own mission to promote biodiversity, sustainable agriculture, and a love for gardening. (You can read more about our values and initiatives on our About Us page.)
A Lasting Legacy in the Gardening Community
The legacy of Seamus O’Brien will continue to bloom for many years. Tributes have poured in from across Ireland and beyond, testifying to the enormous impact he had. His colleagues at the National Botanic Gardens expressed deep sadness at the loss of not just a leader, but a true friend. Celebrity garden designer Diarmuid Gavin perhaps put it best in his heartfelt tribute. Gavin noted that Seamus “has done the State and the gardening world much service,” praising him as “Irish gardening’s greatest ambassador”. Such words highlight how greatly Seamus elevated Irish horticulture on the world stage. Others spoke of his passion and kindness: many in the community describe Seamus as a gentleman and an inspiration, someone whose dedication never waned. It is rare that one person can touch so many facets of the plant world, from restoring historic gardens, to discovering new plants abroad, to educating the public, yet Seamus did all that and more with exuberance.
While we mourn the untimely loss of Seamus O’Brien, we also celebrate his remarkable life. His work at Kilmacurragh stands as a living tribute, a sanctuary of beauty and biodiversity that will continue to enchant and educate future generations. His writings and collected plants ensure that his curiosity and knowledge remain accessible to all who follow. In the spirit of Seamus’s legacy, we at Enniscorthy Community Allotments remain committed to fostering the kind of botanical wonder, conservation, and community engagement that he championed. We encourage anyone inspired by Seamus’s story to carry forward his love for gardening and nature. If you would like to learn more about our ongoing projects in botanical preservation or get involved, please feel free to reach out through our contact page.
Seamus O’Brien will be dearly missed, but his influence will forever be rooted in the gardens he nurtured and in the hearts of those he inspired. May his memory continue to flower in every garden trail, rare plant, and blossoming idea he leaves behind.