Garden Guru: Rock star

The house is situated on a rocky knoll, and commands panoramic views of the lake. Photo / Supplied

Rockeries can be a terrible mistake. At best they look a bit old fashioned and pokey - mats of aubrieta and pinks giving them the garish appearance of the sickly cupcakes.

At worst, they end up as little more than piles of rubble - bits and pieces of stone populated with leaky waterfalls and gnomes.

Yet when you live where Mary O'Connell and Barry Grimmond do, there is no choice but to have a rock garden, for the landscape is defined by the stuff. Rather than fighting this dramatic but inhospitable setting not far from Queenstown, Mary has, over the past 30 years, embraced it. So accepting is she of the terrain that in places she strips off the thin covering of topsoil to expose more of the rugged and beautiful schist strata.

Mary and Barry's present site was bought as a holiday getaway from their base in Dunedin.

Some of the first plants to be popped in were lavender cuttings brought naively from the coast, but more by chance than planning they have lived to tell the tale and now form a dramatic carpet that oozes out over a natural outcrop of rock. Mary finds such Mediterranean plants do well, enjoying the drainage and poor soil so long as they are firmly trimmed well before winter. Any fondness for soft cottagey material, however, has had to be curbed and a more limited plant palette adopted.

At first there wasn't even a proper water supply, apart from the natural spring-fed duck pond which is still the focus of the garden today.

With little or no soil things dry out quickly in the Otago summers, and then have to cope with the biting cold in winter. Macrocarpas have done well as much-needed shelter belts, and Mary has embraced locally abundant natives such as red tussock (Chionochloa rubra) and the elegant plumes of another dwarf toetoe, Chionochloa flavicans. Not all natives do so well, but one welcome surprise has been how hardy the handsome Marlborough rock daisy has proven to be, seeding happily so far south from its natural home.

Trees grow well too, if they get a good hold in the deeper soil that gathers in ravines.

A crow-bar is essential at planting time, and even though Mary reckons all her specimens have a look of tortured bonsai, autumn is a spectacular affair with not just the leaves of deciduous trees, but also rosehips and rowan berries joining the final fling.

In 1984 when they decided to live here permanently, Mary and Barry with architect friend David Stringer planned their third and most ambitious home. Sited on a rocky knoll with the best views over the lake, their vision of a rustic tramping hut that would blend in with the landscape has been magnificently realised.

At the back of the house the land had to be built up to create a plateau, a sheltered space for precious plants that need a bit more soil.

"I wanted this little sitting area to have a raw, unfinished look like the ruined cottages you sometimes see around Central Otago," explains Mary, who did the rockwork herself to get the right effect.

A rustic pergola-style wall wraps around a small sitting area made from recycled timbers and river pebbles with broad flagstones for the floor and brought-in gravel to match for the paths. It's a cosy retreat from the grander landscape of the main garden, and there is room for a few Dunedin treasures like roses, hostas and romantic swags of clematis, which drape themselves over a tough bush of Muehlenbeckia astonii.

Below the house, back when the road was widened, schist rocks were seen more as a nuisance than a valuable commodity, and Mary and Barry were allowed to keep the huge slabs blasted out by the excavations. At first they were simply lined up to form a natural barrier on the boundary, but Mary has since had them reshuffled by digger to become a ridge of giant stepping stones that twist through the oaks like the spine of some half-buried dinosaur. There are views down onto swags of hebe and furry-leaved brachyglottis, and at one point, pencil-thin juniper 'Moonglow' marches off between the rocks.

"I trialled three here to see if they would do as a hedge," says Mary, "but buxus and lonicera have proved a better bet."

Under the deck a huge banksia rose is clipped into a dense hedge, while space behind the house is devoted to vegetables, fruit and nut trees.

Whether it's rocks or plants, much of the joy for Mary has been in enhancing the site using simpler specimens.

Mary's approach has always been to do the best with what she's got, whether choosing the right plant for the right place, or in her struggle with cancer.

"One day it will all get a bit much for us, but for now I want to be out doing the garden - I'm not the sort to be sitting back and looking at it."