Some gardens are notable for the passions and principles that bring them into being. So goes the story of a landscape that delighted thousands at the Los Angeles County Arboretum last spring, and whose continuing evolution may yield new ideas for California gardens.
The Crescent, named for its half-moon shape, had been a gently sloping mound of turf for as long as anyone could remember. Located at center of the Arboretum, the 32,000-square-foot parcel occasionally served as a location for film productions or a site for art, but otherwise did little to earn the water and energy it consumed. It was a landscape awaiting inspiration.
Funded by the James E. Irvine Foundation and administered by LAND (Los Angeles Nomadic Division), an arts organization, Wildflowering L.A., a spirited initiative led by artist Fritz Haeg, has cultivated California native wildflower displays at 50 sites across Los Angeles County. Haeg’s inspiration, to grow wildflowers in diverse and sometimes unexpected places, found purchase in a vast Los Angeles seemingly severed from nature. As Haeg wrote,
“Age-defying thirsty landscapes of clipped evergreen shrubbery and lawns cover this city that supposedly has no seasons, no sense of time, and an aversion to all evidence of aging or death. The story of its native wildflowers is more complex, nuanced, localized and ever changing…the story of the season is told with the timing and extent of the bloom in direct proportion to the rainfall, temperatures, and climate.”
Many of the Wildflowering L.A. sites, which ranged from vacant lots to front yards, juxtaposed gardens of native annuals with asphalt and speeding traffic. At the Arboretum, the expansive meadow planting contrasted with the surrounding Arboretum, a landscape shaped over decades and filled with diverse collections and gardens. Amid the verdant beauty, a highly fruitful collaboration spontaneously began.
From Turf to Wildflowers: A Shared Journey
In 2009, a self-organized team of Arboretum staff and volunteers, led by Leigh Adams and Caitlin Bergman, explored the potential for creating productive landscapes by rehabilitating urban soil. The group reclaimed a small Arboretum storage lot in a non-public area by dramatically improving soils and knocking out curbs to divert water from an adjoining road and capturing hard-surface runoff for irrigation. The resulting garden, called the Permasphere, powerfully demonstrated a number of ecology-based gardening principles and served to galvanize a small community committed to sustainable practices. Yet the garden’s educational potential was limited by its location, which was inaccessible to the Arboretum’s some 300,000 annual visitors, spurring a search for options to bring the garden’s energy and ideas into public view. That opportunity came with Wildflowering L.A.
Haeg’s plan for native landscapes grown among the myriad precincts of L.A. found a home at the Arboretum when Adams and Superintendent Timothy Phillips set out to create perhaps the most spectacular of Wildflowering L.A.’s many sites. They also intended to capitalize on the opportunity to demonstrate various approaches to creating balanced and productive garden ecosystems.
Under Phillips’ direction, turf on The Crescent seemed to disappear overnight. A mechanical sod cutter quickly working across the site produced small mountains of severed grass and soil that served as foundation material to createtopography. Guided by Haeg, a pathway and seating area were established to encourage people to linger and explore. Adams dug swales to intercept, cleanse, and sequester runoff from the surrounding roads. Finally, the remaining piles of sod were put to use in a Hügelkultur demonstration, a centuries-old cultivation technique from Central Europe (see opposite). The long, serpentine hügels (German for mound) gave height and depth to the wildflower displays and tested the effects of microclimate and soil depth on germination and growth.
What is Hügelkultur?
Hügels are mounds made of logs, green waste, organic debris, and soil, oriented into a gentle crescent intended to capture moisture-laden ocean air. This core of logs and grass trimmings and, in our case, sod from the 70-year-old lawn, was layered with soil and backfilled. Because of the density of the logs, it takes longer for them to gather heat during the hot summer days even as the same solar rays warm the soil covering the wood. In the cool of the evening, as Pacific breezes move inland, the humid air encounters the cooler logs within the mound. Just as steamy air in your shower condenses on cooler surfaces in the room (like the mirror), water in the air is forced to condense out into the hügel.
The harvested water begins to break down the logs, creating humic acid, which increases the soil’s ability to hold water and fertilizes new growth on the surface of the mound. The introduction of organic matter dramatically improves our 96-percent clay soil by increasing fertility and biotic activity. The form of the hügel creates areas that are sheltered from winds and areas that receive less sun exposure; thereby maximizing the variety of plants we can grow as well as increasing the surface area available for production.
Weed control was a major challenge as Bermuda grass, crabgrass, and nutsedge posed tough competition for the soon-to-be sown wildflower seed. After a quick dismissal of chemical solutions and a few weeks of hand weeding, the team began “lasagna” mulching. Opening one box after another, they overlapped and blanketed the soil with clean cardboard without colored inks that often contain metals. The cardboard was topped with a thick 6- to 8-inch layer of mulch and everything was deeply watered in. Powered by legions of volunteers and boy scouts, the technique delivered good results, thwarted only by persistent nutsedge.
Using one of our custom mixes—hillside, roadside, coastal, and flatland—more than 20 pounds of Wildflowering L.A.-prescribed seed was sown in early winter. Spread in sand mixtures, bound in mud balls, and tossed by hand, hundreds of volunteers and visitors participated in the process. Tidytips were the first flowers to appear, and a few weeks later their seedheads attracted large flocks of lesser goldfinch. Western bluebirds and phoebes scanned the meadow for prey from tall bamboo stanchions designed to offer nesting sites to native bees. Later, scores of white-lined sphinx moth caterpillars grazed like cattle on arching clarkia stems, transfixing children and parents with their voracious appetites and horn tails. When the caterpillars finally decamped en masse to pupate in the soil, a red-tailed hawk nesting nearby enjoyed an easy feast, hopping on the ground like a robin.
Some public landscapes present gardens and plants to be viewed at a distance, like gallery objects. Others invite visitors to engage and discover within a fully immersive landscape yielding experiences that are spontaneous, self-directed, and unique to each individual. The Crescent garden is in the latter category; its journey from turf to wildflowers was traveled not only by the project team, but also by thousands of visitors, schoolchildren, and tour groups. Over three months, we watched a landscape transform from static lawn to an immersive meadow of stunning beauty and new ideas. More than observers, many became active participants in the garden’s creation.
Surpassing even the new environs it created, the project’s most important gift was the hundreds of questions it generated in a shared testing of ideas. Some Arboretum members visited more often than before, asking “have you noticed the increased bird life?” and “did those seed balls actually sprout?” Indeed, encouraged by learning about hügels and seeing the results, several people started experimenting in their home gardens. The Arboretum’s willingness to experiment seemed to promote a sense of adventure that moved others to take a risk and explore new gardening methods. Whether testing the benefits of Hügelkultur or assessing the ability of sheet mulch to suppress nutsedge, the Crescent engendered genuine curiosity and learning—a sweet result for an institution dedicated to public education.
For Fritz Haeg and Wildflowering L.A., the Crescent offered a spectacular demonstration that the California wildflower displays, so ecstatically described a century ago, are still within reach, and though entirely different in origin and structure, no less inspiring for all who behold them.
[sidebar]Los Angeles County Arboretum and Botanic Garden
301 North Baldwin Ave, Arcadia, California 91007
Looking ahead, the Crescent promises an interesting future at the Arboretum. As wildflowers fade this summer, the new gardens that replace them may draw from sources as varied as permaculture, urban ecology, and Native American foraging traditions. The resulting landscapes, presented as practical experiments, will contest thirsty 20th-century plantings prevalent throughout Los Angeles and seek to assist a mature and challenged metropolis to better manage water, energy, and space.
Wildflowering L.A. Seed Mix
Seed mixes for Wildflowering L.A. were selected and prepared by The Theodore Payne Foundation, a public garden, nursery, and educational resource devoted to California native plants. Four seed mixes were prepared for the project; the “Flatlands” mix, see below, was sown at the Arboretum.
White yarrow (Achillea millefolium)
Winecup clarkia (Clarkia purpurea)
Elegant clarkia (Clarkia unguiculata)
California poppy (Eschscholzia californica)
Bird’s eye gilia (Gilia tricolor)
Tidy tips (Layia platyglossa)
Collared annual lupine (Lupinus truncatus)
Purple needlegrass (Nassella pulchra, syn. Stipa pulchra)