ONE HILL, TWO GARDENS

In Marin County, California, a natural grassland provides the backdrop for an environmentally responsible design

text and photography by SAXON HOLT illustration by GORDON MORRISON

MOST OF US WANT A GARDEN THAT SEEMS COMFORTABLE IN ITS NATURAL SETTING. But gardeners also tend to be plant enthusiasts who want special, exotic plants that remind them of other regions, other cultures. Only the most dedicated native plant enthusiasts have the discipline to keep their hands off, and their gardens free, of “alien” plants. The rest of us are just too tempted by the beauty of nonnative plants to show that much restraint. The challenge of gardening in a naturalistic style, therefore, is to create a special place for nonnative plants so that they can fit in without dominating.

The Marin County, California, garden of Dr. and Mrs. Roger Greenberg meets this challenge brilliantly by juxtaposing an exotic, secluded, inner garden with the surrounding native grass landscape. Between the private courtyard garden and the adjoining open space there is a transitional outer garden dominated by drifts of nonnative ornamental grasses that would not survive in the summer-dry native landscape without irrigation. This naturalistic garden provides a way of dramatizing the neighboring landscape by borrowing its aesthetic without borrowing the actual plants. The Greenberg property thus provides a special opportunity to explore the complex relationship between the garden and nature.

This opportunity has its risks. The land abutting the Greenbergs’ property is the Ring Mountain Open Space Preserve, a distinctive habitat of native bunchgrasses originally purchased by the Nature Conservancy in 1982 and later transferred to the Marin County Open Space District. Like the rest of California’s grasslands, the preserve has already suffered from centuries of accelerated ecosystem degradation. (See “Ornamental Grasses: Boon or Menace?” page 37.) Gardening next to a preserve like Ring Mountain poses the potential threat of introducing new opportunistic plant bullies, and thus contributing to the preserve’s deterioration. For example, certain ornamental grasses, such as purple pampas grass (Cortaderia jubata), which was introduced into California for soil stabilization and which at first appeared to be nonweedy, have since spread beyond control. Any form of gardening that involves ornamental grasses, therefore, requires extremely careful thought and planning.

Talking about Design

When stone is a conspicuous part of either the natural or man-made landscape-think of New England, with its glacier-scraped outcroppings and ubiquitous drystone walls, or those parts of the Southwest where sunset-hued sandstone dominates—it makes good aesthetic sense to incorporate it into the garden. This is certainly true of the site where the Greenbergs constructed their house and garden, which gets its character from numerous large serpentine boulders and their associated vegetation. Serpentine is rarely found on the surface in most parts of the world, but it is common in California (in fact, it is California’s state rock). Its color varies from an unusual gray green to black, and the soils it produces are thin and nutrient poor (and even toxic to many plants). Specially adapted native grasses are among the species that thrive on serpentine soils, and so the pairing of grasses and serpentine provides a perfect model for the designer. Where the soil can be improved by the addition of organic matter, the palette of usable plants increases to include other aesthetically compatible plants such as lavender.

Yet for a naturalistic garden in this part of the world, it would be unthinkable not to use grasses. To ignore the surrounding habitat and impose some other aesthetic onto a parcel of land abutting a preserve would imply an arrogance, an intention to dominate the site. Fortunately, in this garden, the designer and owners came up with a solution that both provided a lush gardening space and celebrated the native grassland—responsibly.

THE SETTING

The property, a one-half-acre lot in a subdivision of custom homes, abuts the preserve more than halfway up Ring Mountain and has a view of San Francisco Bay. The house is set back 100 feet from the street and is carved into the hill, thus creating a dramatic setting and fostering the illusion that the property is part of the preserve.

The homebuilder had originally planned to construct a solid 10-foot retaining wall pushing back the hill behind the house in order to create the garden space. But the Greenbergs sensed this would not fit with the setting, and turned for a solution to Gary Ratway, principal of Integrated Designs in Albion, California. At the time, the Greenbergs knew nothing of Ratway’s spectacular success in designing with grasses at the Matanzas Creek Winery near Santa Rosa, but had been impressed by his work on the Kent Estate, an old Marin County property that had been designed with the help of conservationist John Muir.

After seeing the setting, with its rocks and grasslands, Ratway recognized that there was an opportunity here to create two gardens—one reflecting the Greenbergs’ need for a personal, private garden space, and one that would honor the Ring Mountain Preserve. “The planting scheme, which uses soft, grassy mounds as a seamless transition between the house and open space, was a nobrainer,” says Ratway.

THE OUTER GARDEN

The garden had to be tied to the hillside both physically and aesthetically. Given the nature of the site, the best way to do this was through careful use of rock. Ring Mountain is a grassland preserve because it is dominated by serpentine rock. Serpentine—known colloquially as California blue jade—is toxic to many plants, and as a result gives rise to a uniquely adapted flora, of which grasses are prominent members. Serpentine outcrops thus seemed an appropriate design element for the ornamental grassland that Ratway planned as a transition between the house and preserve.

Fortunately, because the builders of the development had no use for the rock that was being excavated from the other future house sites, there were serpentine boulders to be had for the asking. All Ratway had to do was move them—no easy task, but well worth the effort. As it turned out, the boulders made fine companions for the drifts of ornamental grasses (primarily selections of Miscanthus sinensis, Panicum virgatum, and Deschampsia cespitosa), the rocks offering stability and solidity, the grasses softness, movement, and fine texture. To complement the grasses, Ratway added a long ribbon of lavender that snakes up the hill. The blue violet of the lavender wrapping around the turquoise serpentine makes yet another memorable picture. Sprinkled in among the main groups of grasses are two others, pearly white-flowered Pennisetum orientale and feathery Nassella tenuissima, which offer early-season interest while the larger grasses are bulking up for a later show.

Given its success in capturing the feel of Ring Mountain, it is striking that the outer garden does not contain a single native perennial or grass—it is as much a man-made artifact as the inner garden. The clever placement of dark plants next to light, the undulating masses folding abruptly one into another, and not least the presence of a watering system all indicate that this area is indeed a designer’s contrivance. These are grasslands of the imagination, with echoes not only of the California landscape, but also of the tall-grass prairies of the high plains, and the sweeping savannas of Africa.

THE INNER GARDEN

The transition from the native grassland of Ring Mountain to the ornamental grassland of the outer garden prepares you for the next transition—into the inner garden. Here, behind the entry gate, are color, water, and a lushness that bears little resemblance to the preserve. Yet the inner garden isn’t wholly different in spirit: the boulders sunk into the hill, the spiky texture of phormiums, dusky Pennisetum setaceum ‘Rubrum’, and a sprinkling of tawny nassella, imitating nature’s random spacing, tie the two areas together.

The water begins just inside the gate, where a narrow pond, planted with upright spikes of equisetum and the soft pads of water lilies, follows the path, escorting the visitor to the door. The pond gains in effect by being raised above the level of the path, so that its mirrorlike surface almost seems to contain the hill.

In the back part of the inner garden, Ratway pushed back the hillside and then stabilized it with warm-toned boulders that complemented the house color, thus providing a thread of continuity with the serpentine boulders used in the outer garden. A flight of stone steps rises up the hillside around the golden boulders, which were intentionally provided with numerous planting pockets when they were set in place. These pockets have become a rich and detailed tapestry of color, with phormiums, grasses, santolinas, and lavenders. They also provide space for some of the Greenbergs’ personal favorites, such as Japanese maples and viburnums, which couldn’t possibly blend into the outer garden. At a certain point up the hillside, olives and arbutus mark the border between the inner and outer gardens; beyond that, large stands of miscanthus and panicum separate the garden from the preserve, serving as a reminder of the landscape beyond.

It’s clear that this garden makes no attempt to be a native landscape, but that was never the point. The point was to pay homage to California’s golden hills, while at the same time making sure that the plants in the garden would not escape to wreak further havoc. In this it has succeeded. And the best part is that nature is still there, up on the hillsides of the Ring Mountain Preserve. H

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