The best ferns for Irish gardens: Chelsea gold medalist Billy Alexander's best picks

Irish Times

20-05-2025

In the world of
gardening
, plant collectors are something of a breed apart, with an endearingly boffinish passion for their chosen subject that can often border on the obsessive. In the case of Billy Alexander, owner of the otherworldly Kells Bay House & Gardens in
Co Kerry
, this genial, deeply knowledgeable horticulturist is what the Victorians would once have described as a 'pteridomaniac', a man whose decades-long, unwavering fascination with ferns has shaped his life in countless ways.
It was pteridomania ('fern fever') that first brought him to Kells Bay, a 19th-century hunting lodge overlooking the Iveragh Peninsula with a historic 10-hectare subtropical garden. Home to an extraordinary collection of naturalised tree ferns, its oldest specimen of Dicksonia antarctica – affectionately known as the garden's 'mother tree fern' – is believed to have single-handedly spored the hundreds of others that now flourish in the protected microclimate of Kells Bay's primeval forest.
Originally owned by the Vogel family (and the Blennerhassett family before that), Alexander fell in love with the property on sight and determined to buy it when it came up for sale in 2006. Over the ensuing two decades, he's slowly but surely transformed what was a beautiful but dilapidated building and its overgrown garden into a world-class attraction that now includes a specialist plant nursery, new plant centre, country guest house and restaurant.
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Collecting ferns was like an addiction, I just kept collecting
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His passion for ferns – or monilophytes, as this ancient class of non-flowering plants is also known – has brought Alexander all over the world, travelling through often-remote parts of North Africa, Europe, Canada, the US, South America and Asia in search of rare and unusual species. Highlights include the Juan Fernández islands in search of the cycad-leaved tree fern; southern Chile in search of the diamondleaf fern; Washington state in search of the American sword fern; and New Zealand's South Island in search of species of Dicksonia and Cyathea.
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That same consuming interest has increasingly brought him international acclaim. Just last week, he returned to the hallowed grounds of the Royal Hospital Chelsea in southwest London to begin the painstaking process of creating an exhibit of some of his choicest plants for this year's
Royal Horticultural Society
Chelsea Flower Show (May 20th-24th).*
It's Alexander's fourth time taking part in what's widely regarded as the world's most prestigious gardening show. In 2018 he won silver gilt, followed in 2021 by gold for an outstanding display of ferns in Chelsea's legendary Great Pavilion (a vast marquee famed for its remarkable displays by some of the world's very best nurseries). In 2023, he won gold again, along with Best in Show, plus the prestigious Lawrence Medal awarded for the best exhibit displayed in any RHS Show over that entire year.
For this year's show, he's creating what he reckons is his best yet – ' a seismic step forward' – which is a 120sq m display of over 100 different species of ferns. Every plant in it was lovingly transported to the London showgrounds from Kells Bay last week, after being carefully nurtured for many months in a polytunnel by Alexander to ensure they're in peak condition for their brief moment in the international spotlight.
Entitled Wilde Kells Bay, the display includes tiny, low-growing ground cover species such as Deparia drynaria and the alpine water fern, Blechnum penna-marina. Others, such as the golden tree fern, Dicksonia fibrosa; the New Zealand tree fern, Dicksonia squarrosa; the black tree fern, Cyathea medullaris; and the Norfolk tree fern, Cyathea brownii are towering giants with dramatically arching, shuttlecock fronds so tall that some had to be loaded into the lorry at a perilous angle in order to make them fit. (Hannon Transport was the firm entrusted with the task of getting this precious living cargo safely to London without damage.)
Billy Alexander's Kells Bay House & Gardens in Co Kerry
Billy Alexander's Kells Bay House & Gardens in Co Kerry
Over the course of this week, Alexander and his four-person team have been putting in 12-hour days to complete the exhibit, which will be formally judged very early next Monday morning on what's known as Press Day.
The culmination of several years of meticulous planning and expert plant husbandry on Alexander's part, it's nail-biting stuff. That's all the more so given that this year he's also been invited by the society to take on the role of RHS judge of some of the other displays (not in the Great Pavilion), a job that will require him to race into the London showgrounds shortly after dawn to carefully water his own exhibit before putting on his judge's hat.
Will he equal or even surpass
his 2023 achievement
? Alexander's far too modest to say, but like most, I'm predicting another triumphal result.
*Billy Alexander was awarded a gold medal for his fern collection at the Chelsea Flower Show on May 19th, 2025. The headline was changed on May 20th to reflect the win.
Great ferns for Irish gardens: Billy Alexander's top 5 picks
Billy Alexander is a rare tree fern cultivator and owner of Kells Bay Gardens in Co Kerry
Polystichum polyblepharum: 'This fern is just such a great all-rounder; it's evergreen, exceptionally tough and hardy, and with such an exceptionally long season of interest that it somehow manages to look superb for at least 10 months of the year.'
Blechnum novae-zelandiae: 'A fantastic, damp-loving, evergreen fern that's native to New Zealand, Chatham Islands and the Kermadec Islands. At Kells Bay we grow it very close to the garden's waterfall, where it flourishes in the moist conditions created by the water spray.'
Todea barbara: 'A clump-forming,
statuesque, evergreen species
commonly known as the crepe fern or king fern, it's the Southern Hemisphere's equivalent of our own native royal fern, Osmunda regalis, and yet at the same time it's so different. At full height, it can reach up to five feet tall and is a majestic species.'
Polystichum neolobatum: 'A very hardy, very beautiful, clump-forming, slightly tropical looking fern native to parts of the Himalayas, Japan and Taiwan, this thrives in light shade and a moisture-retentive but free-draining neutral to acid soil. Well-established plants will also cope with somewhat drier growing conditions.'
Athyrium niponicum var. pictum 'Red Beauty': A deciduous, very ornamental variety known as the painted lady fern that's happy in shade and a moist but well-drained, humus-rich, neutral to acid soil, this is particularly early to emerge and is a fantastic choice for a spring garden. I love it for its colourful, delicate fronds, which become flushed with silver and burgundy as they mature.'
This week in the garden
Continue to harden off tender, heat-loving plants in preparation for transplanting them outdoors at the end of this month, taking care to bring them back under cover if night frost is forecast, or the weather is unseasonably cool and windy.
Unless you want to encourage them to self-seed, it's best to deadhead the faded flowers of spring-flowering bulbs to encourage a good flowering display next year. For the same reason, avoid cutting back their foliage until it's very well faded, which allows the bulbs to gradually draw back down the energy and nutrients stored within them.
Dates for your diary:
An Fómhar Fiáin; Ireland's Wildfood Plants
, an exhibition of botanical art by the Irish Society of Botanical Artists, on display at the National Botanic Gardens, Glasnevin, from Saturday, May 17th (from 2pm) until Sunday May 25th.
irishbotanicalartists.ie
.
National Biodiversity Week Ireland 2025
, until May 24th, with a fantastic range of activities taking place around the country including talks, workshops and field trips.
biodiversityweek.ie
.
Grow Wild, the RHSI Russborough Garden Show
, Sunday, May 18th, Russborough House & Gardens, Blessington, Co Wicklow. With garden tours, practical demonstrations, plant stalls, and garden talks.
rhsi.ie
.