Overview
The golden Leyland cypress in half the front gardens of Ireland — ‘Castlewellan Gold’ — was selected here, from a single mutant seedling spotted by the park’s director in 1963. That is the kind of collection this is: a working arboretum begun in 1740, now holding more than 30 champion trees inside Castlewellan Forest Park in County Down. It covers about 120 acres within the wider 460-hectare park, with surfaced paths threading through mature woodland, open glades and formal avenues.
The one tree to seek out is the multi-stemmed giant sequoia voted Northern Ireland’s Tree of the Year in 2018.
A living history
The arboretum was first planted in 1740, and expanded dramatically in the mid-19th century under the 4th Earl of Annesley, who commissioned the conifer avenues that still frame the grounds. Specimens arrived from Asia, Australasia and the Americas — Athrotaxis, Japanese maples and giant sequoias planted in the 1850s among them. The park passed to the Forest Service and opened to the public in 1967; recreation is now run by Newry, Mourne and Down District Council.
The site’s best-known export is the Leyland cypress ‘Castlewellan Gold’, selected here in 1963 by park director John Keown and since propagated across Europe and North America. Walk the paths and you are in the original nursery of a plant now sold worldwide.
Walking the grounds and tree highlights
The arboretum is best taken on foot. The surfaced Arboretum Path is flat and buggy- and wheelchair-friendly, passing the most significant specimens; the longer River Trail follows the watercourse over rougher, uneven ground, so wear proper shoes after wet weather.
Along the way, look for:
- Giant redwoods (Sequoia sempervirens) – Among the tallest trees in the British Isles, their trunks dominating several clearings.
- Monkey-puzzle trees (Araucaria araucana) – Slow-growing, prehistoric-looking specimens with stiff radial branches.
- Rhododendron slopes – Blocks of pink, purple and white across the lower ground from late April into June.
- Champion trees – More than 30 recognised as the largest or tallest of their kind in the country.
One honest caveat: the walled Annesley Garden at the heart of it all is closed for a £5.5 million restoration — funded half by the National Lottery Heritage Fund, half by the council — so for now the best of the trees are along the open paths rather than behind the garden walls.
The rest of the forest park
Beyond the trees, the wider park has plenty on:
- Peace Maze – Built in 2000–01 from 6,000 yew trees, it was the longest permanent hedge maze in the world until 2007, and sits beside the arboretum entrance.
- Castlewellan Lake – A 40-hectare lake under the Mournes, with rowing boats and fishing spots (permit required for angling).
- Mountain biking – A graded trail network for beginners to advanced riders. Mountain bikes, e-bikes and canoes hire from the Grange Yard; book ahead in peak season.
- Family play – A children’s play area and short adventure course near the courtyard.
The Grange Coffee House opens daily from 1 May to 30 September, and at weekends from 1 April to mid-November.
Conservation and recognition
In May 2018 the International Dendrology Society awarded the site a plaque for a “dendrological collection of exceptional merit” — the same year its multi-stemmed giant sequoia took Northern Ireland’s Tree of the Year. Management focuses on protecting veteran trees and balancing public recreation with habitat.
Wildlife and seasonal visits
The woodland supports red squirrels and pine martens along the quieter edges, otters near the lake, and woodpeckers and owls through the year. Timing shapes the visit:
- Spring – Rhododendrons and magnolias against the evergreen backdrop; soft ground and early wildflowers in the glades.
- Autumn – Deciduous sections turn amber and russet, light filtering through the thinning canopy — the photographers’ season.
- Winter – Evergreens take over, the paths empty, and frost or mist settles in the valleys.
Practical information and getting there
- Admission: Free on foot. Cars pay £5; an annual permit is £40, or £25 concessionary.
- Accessibility: The Arboretum Path is surfaced and suitable for wheelchairs and pushchairs; the River Trail is uneven. Wheelchair-accessible toilets are on site.
- Facilities: Coffee house, toilets and parking near the main entrance; trail maps on site.
- Dogs: Welcome on the main paths; keep them on a lead near wildlife and livestock.
- Getting there: From Belfast, take the A24 and A50 south, or the A2 via Newry and the A25, into Castlewellan; the park entrance is signed from the town. Regular buses run from Belfast and Newry to Castlewellan, a short walk from the park boundary.
The walled garden is shut for restoration, so for now aim for the surfaced Arboretum Path — flat, buggy- and wheelchair-friendly, and free if you walk in from the town rather than paying to park.