We are late arriving at Annes Grove in Castletownroche, Co Cork. I'm sorry to have kept Patrick and Jane Annesley, the owners, waiting. But I'm glad I get to see the creamcoloured, 18th-century house glowing in the evening sun. That is, what you can see of it - because it is almost consumed by the immoderate, furry growth of an Actinidia vine. The chunky, rounded leaves and hairy stems - which advance two metres a year - surge over the portico, up the walls, across the windows and reach above the roof, questing for a foothold in the sky. "You need a ruined skyscraper to accommodate it," says Patrick.
The actinidia was here many decades before Patrick and Jane arrived from London in 1976. It may have been planted by his grandfather, Richard Grove Annesley, who inherited the north-Cork demesne at the beginning of the last century. He was a keen plantsman, sponsoring some of Frank Kingdon-Ward's first plant-hunting expeditions to Tibet and Nepal. Rhododendrons grown from seed collected on those trips still thrive in the woodland garden, filling it with luminous blossom in spring.
At this time of the year, it is the turn of the New Zealand lacebarks (Hoheria), which light up the woods with their thousands of starry, white flowers. Two species, Hoheria sexstylosa and H. populnea, have crossed and their progeny has sprung up all over the place: "It's the great weed around here." The "weeds" - cultivated plants that have spread by seed or layering, or by runners or roots - are part of the great charm of Annes Grove. They merge artlessly with the native plants in the sloping acreage, making it one of the finest naturalistic, "Robinsonian" landscapes in the country. The Irish-born William Robinson (18381935) originated the idea of planting native and introduced species together in an informal manner in a natural setting. He would have approved heartily of the imaginative marriage of wild and tame at Annes Grove.
This union is sensational in the dramatic and jungly river gardens, where the River Awbeg courses though a sunken glen. The river was diverted in the 18th century so it could be seen from the house, and channelled around an island. By the time Richard Grove Annesley came here a century and a half later, it had silted up and the valley was a marshy muddle. He employed soldiers from the barracks at Fermoy to clean out the river and to span it with numerous rustic bridges.
His inspired plantings are now voluptuously mature: under a leafy ceiling of cordyline, cypress, willow, cherry, bamboo and katsura (Cercidiphyllum japonicum), the river banks and snaking paths are hemmed in with the gigantic foliage of gunnera, skunk cabbage, phormium and umbrella plant. (Darmera peltata). Mass-gatherings of day-lily, astilbe, and pale yellow Primula florindae make welcome patches of colour in the watery, green scene. Native meadow sweet, purple loosestrife and marsh valerian mingle freely with the exotics.
You can lose yourself here for hours, tunnelling under the thorny-ribbed tents of gunnera, swishing through the bamboos and pounding over wisteria-clad bridges. You might get a surprise soaking from the rain that collects in the dishes of the umbrella plants ("when we want to be nice to our visitors someone goes around every morning and tips the water out of them"). In this private adventure, the rush of the river is always in your ear - and on lucky occasions, the rusty, primordial caw of a resident raven. Before leaving the river garden, you must pause to muse at Spenser's Well, where the poet - who lived upstream - was supposed to have refreshed himself. His thorn tree is also here: "The original one died, so we hastily planted another, and this immediately became `Spenser's thorn,' " Patrick admits.
Back in this world - but a world that is still old and appealing - the walled garden weaves its own spell. Ribbons of box-hedging ripple along beside the path, and a relaxed herbaceous border billows on either side of a walk knit from slabs of Clare limestone. Shallow steps, edged with sharply-scented lavender and frothy lady's mantle, lead to a curious little summer house on a miniature mount, backed by an autumn-flowering border. The view from up here shows that the central axis - from the mount to the end of the herbaceous border - is slightly skewed, but this error (or perhaps it is just the result of pure nonchalance?) makes the garden even more engaging and human.
Behind the yew hedging that lines the herbaceous border is a secret pond-garden with a serpentine pool. "It was put in under my grandmother's supervision. It leaked for 100 years," remarks Patrick. Echoing in miniature the mood of the river garden, it is verged with dwarf conifers, cordylines and a fantastically gnarled birch that was twisted and shaped with "wires and wounding, like a bonsai on angel dust". The fat leaves of bergenia and hosta, and the spires of galtonia and eucomis complete the picture.
Beyond this, an orderly nursery and plant-sales area is guarded by the tiny terrier, Zsa Zsa, who has ideas far above her petite stature. The preserve of one of the gardeners, Rosamund Henley, it is filled with choice perennials, including a good range of salvias, the oriental poppy `Patty's Plum' and the fabulously phallic Beschorneria yuccoides. It's the perfect place to stop a bit and to carry away a souvenir of this magical garden.
Annes Grove, Castletownroche, Co Cork is open Monday to Saturday, 11 a.m.-5 p.m., Sunday 1-6 p.m. until September 30th. Other times by appointment. Admission £3. Plants for sale in walled garden. Inquiries: 022-26145.
Diary date: September 1st to 3rd, residential flower-painting course with Patricia Jorgensen at Ballinkeele House, Ballymurn, Co Wexford. Fee, including accommodation and meals, £235; or £60 daily, including lunch and coffee. Inquiries: 053-38105.
Jane Powers is at jpowers@irish-times.ie