Andrea chran's California garden | House & Garden

Richard Bloom

It is easy to get lost in the wooded hills above the old town of St Helena in California’s Napa Valley. But there are worse places to lose your bearings – the meandering roads on these steep slopes climb through thick forests of native coastal and evergreen oaks, revealing countless secret valleys strewn with boulders and sprouting native grasses.

A rather special house can be discovered at the end of one such road, where the landscape architect Andrea Cochran has enhanced an existing garden with a series of subtle tweaks to the landscape. This approach is becoming popular with designers here, with the emphasis on using native or adaptive plants for a sense of continuity with wider nature. The word ‘adaptive’ is used for non-natives that can cope with the dry summers and wet winters.

As Andrea herself puts it, ‘Our work draws boundaries with a controlled palette of materials, creating permeable edges that blur the line between the natural and built environment. This exercise in restraint heightens a sense of the elements – texture, light and movement.’ That can certainly be said to be the case at this project, where the design subtly draws attention to aspects of the landscape without it feeling like an ornamental addition.

The property consists of two single-storey buildings – a main residence and a guest house – on a plateau on top of a ridge in an undulating landscape that falls away steeply on two sides. A rectangular swimming pool at a lower level is hidden from view. The buildings, by architect Michael Maltzen, are pleasingly rustic: rough fieldstone walls and metallic-grey angled roofs conspire to create the impression of agricultural buildings. This aesthetic brings to mind Frank Lloyd Wright’s words: ‘What is the reason you want to build there? Find out! Then build your house so you may still look from where you stand upon all that charmed you, and lose nothing of what you saw before the house was built, but see more.’

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Andrea’s main intervention was the creation of a straight walkway of stone slabs from the parking area to the house. The route is waymarked by a single line of shiny stainless-steel poles and flanking plantings of Elegia tectorum, a reed-like South-African grass. A number of pre-existing mature evergreen oaks have been retained, which add great character. The path opens out to generous terraces around both buildings, the edges of which seem to merge with the hillside grasses. A metal figure by Antony Gormley stands sentry by the guest house door, one of several sculptures – including pieces by Anish Kapoor and Jim Hodges – around the property.

The Californian designer and grass specialist John Greenlee had earlier created meadow plantings featuring tough grasses, such as Festuca mairei and Pennisetum spathiolatum, and shrubs, including the California fuchsia, Epilobium canum, with scarlet trumpet flowers. Working with the owners, who have a strong interest in horticulture, Andrea augmented these with the more ornamental Muhlenbergia lindheimeri and ceanothus, with Carex pansa and sedums between the stone pavers on the terraces.

The steep slope below the property had been planted with plum, apple, citrus and pomegranate trees. After replenishing the soil around them, Andrea’s team replanted with Lomandra ‘Breeze’, salvias, Olea europaea ‘Little Ollie’, ceanothus and rosemary bushes. A grove of magnolias further down produces white blossom in spring and groups of camellias thrive under the oaks.

Based in San Francisco, Andrea is one of the most acclaimed garden designers in the US, and is known for designs that find a balance between cool, artful composition and the soul of the existing landscape. This Napa Valley plot is a prime example.

Andrea Cochran Landscape Architecture: