British imports

SOMETIMES you have to travel halfway around the world to solve a problem in your own backyard, a point Southern California gardeners may want to note as they face drought, limited water supplies and air pollution, not to mention threats posed by encroaching development, invasive plants, synthetic pesticides and fertilizers -- our list of woes goes on and on.

For some welcome solutions, look to none other than the Chelsea Flower Show, arguably the world’s finest garden exhibition, held by Royal Horticultural Society in the heart of London.

Although you might think of English gardens as flowery borders and clipped hedges, the May show proved England’s position as the center of progressive gardening. The event featured close to 50 display gardens, some nearly a quarter-acre large, and most created by Europe’s leading landscape designers. Sustainability was the unspoken theme, broadly interpreted and elegantly executed. Though the spaces were created for Chelsea, the concepts and philosophies spoke directly to California.

The ultimate in sustainable design and winner of best-in-show was “600 Days With Bradstone,” a stunning combination of the ancient and the futuristic, designed by Sarah Eberle and sponsored by the hardscape company Bradstone. Eberle spent eight years researching what she calls a “terrestrial space garden” that would support an astronaut for an extended stay on Mars. That may sound far-fetched, but many of the concepts apply to any homeowner looking to create an interesting, environmentally conscious space despite challenging natural conditions.

Eberle’s garden was enveloped in rammed earth walls whose strata of red, burnt orange and copper were embedded with aggregate. The idea was to emulate walls formed using materials from the red planet’s metal-rich rock surface. The wall also created a primeval backdrop that set the mood.

The designer chose some plants as a food source, others for medicinal purposes and still others because they would contribute a significant amount of oxygen to the atmosphere. Most nonedible selections were drought-tolerant because, Eberle realized, the only way to get water would be to extract it from the permafrost.

To manage such a limited resource, she clustered plants into distinct zones based on water needs, a practical technique whether on Mars or Mount Washington. Eberle created a “working” area of the garden with essential crops -- squash, tomatoes, kale and other dietary basics -- along with luxuries such as olives, figs, grapes and pistachios, all requiring a fair amount of water. Medicinal plants including calendula and opium poppy were placed here as well.

A separate low-water living area of the garden included a sunken, crater-like pod for rest and relaxation. Enormous, lens-shaped concrete planters overflowing in colorful flowers were suspended from arching copper arms. A hanging chair shaped like a geodesic globe hearkened back to California in the early 1970s. Plantings here were mostly succulents such as agave, aloe and echeveria, supplemented with other flora native to arid environments.

Eberle’s design wasn’t a pretty garden per se, but pretty wasn’t the point. It made visitors stop and think: What can this experiment teach us about making our own gardens more ecologically sophisticated?

In contrast to Eberle’s design, the Sustainability Garden sponsored by the hardscape company Marshalls was sleek, comfortable and down to earth. Designer Roger Smith created the space to demonstrate that you don’t need to sacrifice style “in the pursuit of an environmentally aware domestic garden.” The space could pass for something you might see at a contemporary home in the Hollywood Hills or a midcentury modern in Pacific Palisades.

Rather than disposing of surplus soil from the garden’s construction, Smith mounded it around the walls of a studio for temperature and noise insulation. Instead of stabilizing the soil with cement, he called upon gabions, metal cages filled with recycled stone rubble.

Gray-water systems might become more popular in California if they were as elegant as Smith’s. Water captured from sink and shower drains emerged through an elegant spout and was channeled through a reed biofilter. Once processed, the water flowed beneath a graceful deck and into a pond surrounded by white calla, purple water iris, white flag iris, ferns and burgundy-leaved Ligularia. The water flowed on to organic flower, herb and vegetable beds as well as olive trees and grapevines.

Recycled glass steppingstones set just above the pond water’s surface formed a sort of floating pathway that connected a studio to the working area of the garden. Smith filled flower beds here with drought-tolerant Mediterranean plants that would have been equally at home in Pasadena. The palette included intense blue-flowering lavender, copper-leaved sedge, gold-flowering mullein and purple-headed ornamental onion, all planted among edibles such as blood-red beets, gray-leafed artichoke, feathery fennel and purple-blushed culinary sage.

In the center of each bed lay a blue glass-and-steel pyramid fitted with a solar collector that, according to the designer, powered batteries for LED fixtures set into recycled glass walls surrounding the pond.

Grapevines, olive trees and walls of recycled scaffold boards screened compost bins, reminders that home composting not only recycles critical nutrients back into the garden and reduces the need for imported fertilizers but also reduces the amount of garden waste taking up landfill space. Less trash means fewer carbon emissions from landfill-bound trucks too.

On a different scale, Amnesty International’s Garden for Human Rights was a sustainable rooftop retreat in an urban setting. Designer Paula Ryan used responsibly sourced hardwood for decks and seating, and the reflecting pool was made of recycled plastic.

The rooftop, planted with succulent sedums and other low-water plants, did its part to absorb the reflected sunlight that often makes cities hotter and drier. Elsewhere in the space, drought-tolerant echeveria served as a strong architectural form and as the basis for a blue-green palette. The succulent’s colors were echoed by olive trees and a border of cold-hardy eucalyptus called cider gum, which provided shade and screened out neighbors.

Choosing drought-tolerant plants, organizing the garden into water- efficient zones, recycling gray-water and composting are all techniques whose time has come -- to the forward-thinking world of Chelsea as well as residential gardens right here in Southern California.

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Garden delights

For more information and pictures of the demonstration gardens at the Chelsea Flower Show, considered by many to be the finest botanical exhibition in the world, check out these websites:

RHC: The Royal Horticultural Society of England, organizer of the show, has stories, pictures, video and a blog at www.rhs.org.uk/chelsea.

Mars: For more information on the Mars garden, check out the website set up by sponsor Bradstone at 600dayswithbradstone.co.uk.

Sustainability: For more on the Sustainability Garden, go to the website set up by the garden’s sponsor, British landscaping company Marshalls, at www.marshalls.co.uk/chelsea.

BBC: Extensive coverage of the show is available from the BBC at www.bbc.co.uk/gardening/ flower_shows/chelsea_2007.

-- Nan Sterman