The reward for the long drive is an enchanting visit to a remarkable garden, writes JANE POWERS

THE WEATHER AND the signposts are not kind to garden visitors in Donegal: there’s too much of the former and not enough of the latter. But, believe me, it’s worth braving both, because there are some fine horticultural spots up here. On a recent visit, we spent some time at three of them, and each was a treat. I’ve written before about Elizabeth Temple’s magical walled garden (donegalgardens.com) at Salthill, just outside Mountcharles, so won’t again, except to say it is even better than when I saw it last four years ago. And I’ve no room to do justice to the carefully and beautifully restored Oakfield Park, near Raphoe (oakfieldpark.com), the home of Gerry and Heather Robinson, so I’ll save that for another time – although let me just mention that if you fancy visiting, you’ll need to hightail it up there before the end of the month, when the season closes for the year.

So instead, I’d like to park myself for the rest of this page at Glenveagh Castle Gardens (glenveaghnationalpark.ie). This is one of the most remarkable gardens on this island. It is concealed in a remote and seemingly inhospitable place, in the middle of Glenveagh National Park in the north of the county. You drive for miles (usually more than you intend, thanks to the non-signposts) through brown-russet-and-purple bog and mountain, hop on a shuttle bus, (€2) and are delivered through the gates. The great, grey, granite bulk of the Victorian castle, built in the Scottish Baronial style, rises up before you, laced in by woodland on three sides. On the fourth, it towers over Lough Veagh, which fills a crease in the glen below with its dark, peaty waters. It is the protection of the valley, and the temperature-regulating deep body of water that have partly made gardening here possible. But it is also thanks to the shelter belt of Scots pines, planted in the 1880s by Cornelia Adair, American-born wife of Laois man John Adair, who built the castle.

Within this mountainy, watery, woodland-lined bowl there are areas of intense horticulture, initiated by Mrs Adair, and added and improved upon by a series of owners, including, today, the State. The 11-hectare garden has been cultivated almost constantly for more than a hundred years, giving it an unusual sense of continuity. Its present head gardener is Séan Ó Gaoithín, who is mindful of the historical importance of the property and its plant collections, while also recognising the need to keep it relevant today. The staff is tiny: four full-time gardeners augmented by “anyone I can beg, borrow or steal,” says Ó Gaoithín.

The setting of the gardens is spectacular, but so also is the planting. Within the sheltered microclimate, frost is rare (last winter was an exception), rainfall is high, and growth is lush. Big-leaved rhododendrons, elegantly-fronded tree ferns, and plump Cordyline indivisa make this a surreal, subtropical oasis in the hostile mountain landscape. Much of the planting dates back to the 1950s, 60s and 70s when the last private owner, Henry McIlhenny, employed – among others – British plantsman and designer James Russell of Sunningdale Nursery, and later, American garden designer Lanning Roper.

There are numerous smaller gardens, walks and terraces in clearings in the woods, but their masterpiece is in the one-hectare Pleasure Grounds, a sunken garden at the heart of the estate. Here the thin peaty ground had been improved by Mrs Adair in the previous century, when she imported hundreds of cartloads of local topsoil. She had put in a long, sinuous lawn, and planted trees, including some fine Japanese maples. But Russell’s and Roper’s later plantings give this spot an otherworldly atmosphere. Silver, grey and dark-leaved foliage – including Brachyglottis ‘Sunshine’, blue cedar, astelia, hoheria, Pseudopanax ferox and P. crassifolius – shimmer and recede in the blue, misty light on one side of the lawn. On the opposite side, rhododendrons, southern beeches, magnolias and other choice shrubs and trees are underplanted with waves of herbaceous perennials including hosta, astilbe and rodgersia. These create a many-shaped, interesting foil for the woody stuff above. To our contemporary eyes it looks completely right, but at the time of planting, this was revolutionary. Shrubs and trees were not usually combined with such highly textured swathes of perennials.

Lanning Roper, who had attended Harvard with McIlhenny, was also responsible for redeveloping Mrs Adair’s half-hectare walled kitchen garden, and turning it into an ornamental French-style jardin potager with vegetables and flowers growing together in formal beds. Today, with its smaller staff, the walled garden is less manicured than in McIlhenny’s day, but it is totally enchanting with its intermingling of workaday vegetables and ornamental plants. All are growing in deep, dark soil, laboriously manured and dug over each winter. The digging technique has been the same for decades, and many of the plants are the same varieties grown by McIlhenny. Among these are the red dahlia ‘Matt Armour’, named for his head gardener, and grown since the 1930s. More recent additions include Irish vegetables, collected and grown by Ó Gaoithín, in the 15 years since he has been head gardener. One of these is the massive, metre-wide Gortahork cabbage from the north coast of Donegal. It’s so big and nutritious that “you need only a leaf of it for your dinner”. Which is a bit how I feel about the garden at Glenveagh: it’s huge and nourishing and historic, and it would take days to get through the whole of it.

For more details on Donegal gardens, see donegalgardentrail.com.