New Entrance Garden at UC Botanical Garden: An Explosion of Arid Exotica

By: Nathan Smith

Nathan Smith is a horticulturist for the University of California Botanical Garden at Berkeley, where he is responsible for maintaining…

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The award-winning UCBG garden at the 2000 San Francisco Flower & Garden Show provided inspiration for, and featured many of the arid-exotics now employed in, the new entrance garden. Photograph by Stewart

The award-winning UCBG garden at the 2000 San Francisco Flower & Garden Show provided inspiration for, and featured many of the arid-exotics now employed in the new entrance garden. Photograph by Stewart

After decades-long efforts, the University of California Botanical Garden at Berkeley has finally constructed a dignified new entrance to introduce the public to the collections within the garden fence. The hardscape and conceptual design were created by the landscape architecture firm of Reed Dillingham and Associates of Berkeley. The horticultural treatment was designed and installed by a team of the garden’s horticulturists, including, Jerry Parsons, Eric Schulz, Colin Baxter, Anthony Garza, and the author.

For many years, a battered, barbed-wire-topped, chain-link fence framed the gateway to the University of California Botanical Garden at Berkeley (UCBG). The gate opened onto an expanse of sloping, degraded asphalt that was the garden’s original parking lot—hardly a flattering introduction to one of the most diverse collections of plants in the United States. In addition to the abysmal aesthetics, the entrance suffered from functional shortcomings. Both service vehicles and pedestrians used the same entry point. Rumbling diesel dump trucks and hordes of small children often converged simultaneously on the entry resulting in a messy and dangerous commingling. The expanse of asphalt served as a gathering point for groups and tours, yet sloped to a degree that exceeded government standards for wheelchair accessibility.

To understand how a respected, established university botanical garden could present such an entry to the public requires an understanding of the garden’s history. The garden was a research facility for the exclusive use of university staff, students, and faculty, from the time of its establishment in the 1890s until 1969, when it was opened to the public. Now, with declining university funding, the garden relies increasingly on its membership and the public to continue its operation. Along with a research focus, the garden is working to expand its audience and improve public access and safety. A crucial step in that direction was the construction of a safe and welcoming entrance.

Although the need for a new entrance had been clear for decades, it was not until Dr Paul Licht, former dean of the College of Letters and Science, arrived as director in July, 2003, that the garden was able to get the project off the ground. Dr Licht brought a heretofore unknown drive to the directorship in his “retirement appointment” to the garden. Volunteering months before he was actually appointed director, it was clear that he was a man on a mission. In addition to his considerable contributions, both personal and financial, he cajoled family members, friends, and anybody else who would listen into contributing to the construction of a new entrance. Within two years, the new entrance was in place.

The entrance plaza from below; the hundred-year-old Mediterranean fan palm (Chamaerops humilis) is just to the left of the new gate. Photograph by Janet Williams

The entrance plaza from below; the hundred-year-old Mediterranean fan palm (Chamaerops humilis) is just to the left of the new gate. Photograph by Janet Williams

A New Infrastructure

Several considerations, besides the obvious safety and accessibility issues, were critical in designing the new entrance infrastructure. The style of the entrance needed to resonate sympathetically with the garden’s canyon setting and the architectural style of the nearby Berkeley neighborhoods. The design also needed to provide a suitable gathering area while maximizing the planting space for a proper botanical introduction to the garden.

The Dillingham solution created separate service and pedestrian entries, and tackled the topography by carving two level terraces out of the former sloping lot. The terraces provide suitable gathering areas and a comfortable space in which to orient oneself to the garden. A massive flat boulder set into the lower terrace provides a focal point and informal seating. Connecting the terraces are a broad flight of stairs and a curving wheelchair-accessible ramp. The terraces were surfaced with an alternating pattern of conventional, stained concrete and an innovative pervious concrete that allows rainwater to percolate into the soil, thereby reducing runoff and improving the hydrological function of the garden as an integral part of the Strawberry Canyon watershed. The differences in color and texture of the two materials contribute to the design’s appeal.

The pedestrian and service entries were separated and set well back from Centennial Drive, improving both safety and traffic flow by creating an unloading space where vehicles and tour groups can pull safely out of the flowing traffic. Framing the pedestrian entrance are massive, rusty-stained concrete pillars, artfully eroded to reveal the smooth pebbles that run, river-like, through them. A Craftsman-inspired pergola is suspended over the pillars, and an attractive iron gate replaces the bent barbed-wire behemoth that formerly regulated traffic flow into the garden. The separate, remote-controlled service gate represents a major functional improvement as well. A new redwood fence links the two gateways with the nearby entry kiosk.

Once the concrete, steel, and wood were in place, the Garden’s horticultural staff took over to finish the project, creating a new landscape with rocks, soil, and specimen plants. The design process unfolded organically over a period of several months while the hardscape construction proceeded. Our team began gathering potential plants for use, taking cuttings and divisions from the collection and identifying sources for the plants that would need to be purchased. Virtually all the plants in the UCBG collection have been collected with permission from documented wild sources, and we strove to maximize the use of wild-collected material for the entry garden. Mountain States Wholesale Nursery donated additional key specimen plants from their display at the 2003 San Francisco Flower & Garden Show.

Horticultural Preparation

While plants accumulated in the nursery, we began, as good gardeners do, with the soil. After decades beneath asphalt and months of compaction by the heavy machinery, the soil in the new planting areas was a sickly, impenetrable amalgam of clays and old asphalt. Amendment was not an option; we had to replace the soil. Excavating twelve to eighteen inches, even with the use of heavy machinery and student assistants, was miserable but critical work. Through a combination of excavation and mounding, we created deep beds of a custom soil mix from American Soil Products for the new plantings.

The planting design revolved around several dramatic specimen plants. To anchor the largest planting bed, we chose the hundred-year-old Mediterranean fan palm (Chamaerops humilis) that was used to such great effect in the UCBG display at the 2000 San Francisco Flower and Garden Show. Salvaged from the university’s Gil Tract, the palm is believed to have been part of the original plantings when the university developed that area in the late 1800s. Moving the five-and-one-half-ton boxed tree required the use of a large crane. We measured, and re-measured the planting hole and the spread of the canopy to ensure that it would fit in the narrow planting bed. When the massive plant was twirling slowly twenty feet off the ground and creaking in its rotting box, there were a few moments of stomach-turning doubt, but, with just a little finessing, the palm fit into place without incident.

Next, we went to work with the rock. A dry-stone wall was constructed to enclose the root mass of the palm and to create a planting bed to support the edge of the curving ramp. Large boulders were placed in the beds for horticultural and aesthetic reasons. Special care was taken to blend the variations in rock textures and colors, and boulders were placed to create a feeling of timelessness and permanence in this newly constructed landscape.

The blue foliage of a South African cycad (Encephalartos sp.) echoes the colors of a eucalypt (Eucalyptus orbifolia) behind. Photographs, by Anthony Garza, except as noted

The blue foliage of a South African cycad (Encephalartos sp.) echoes the colors of a eucalypt (Eucalyptus orbifolia) behind. Photographs, by Anthony Garza, except as noted

The Plantings

The great challenge in working with such a diverse garden was not deciding which plants to use, but deciding which plants not to use. We employed considerable restraint in order to keep the plant palette cohesive and culturally consistent. Even so, the planting scheme quickly diversified to over 170 taxa. Jerry Parsons led the team and brought his refined design sensibilities and familiarity with the Australasian flora; Colin Baxter offered horticultural experience from his native Australia and his knowledge of the flora of the Mediterranean region and the Canary Islands; Eric Schulz contributed a subtropical flair with his expertise in the flora of Mexico and Central America; Anthony Garza shared his passion for monocots and the flora of the New World deserts; and I rounded out the team with my understanding of our native Californian flora.

I had feared our diverse interests would lead to a contrary design process and, ultimately, an incoherent design, but we were unified and inspired by the example set by the garden’s exhibit at the 2000 San Francisco Flower and Garden Show. That installation utilized bold foliar texture and intriguing forms to create a garden of year-round interest. The imaginative assembly of such an unusual and diverse planting palette by Jerry Parsons and David Brunner impressed the judges, and the garden was awarded thirteen gold medals, including the Golden Gate Cup “Best of Show.” While that show garden was spectacular, it was a temporary installation. We now sought to translate that vision into a real-world, outdoor garden that would thrive and provide interest and inspiration for years to come.

The theme of the new entrance garden continued to develop focus as planting proceeded, assisted by breakthrough additions of plants not originally in the planting plan. We were challenged by the twin goals of creating an entry planting that reflected the diversity of the garden while maintaining a cultural and aesthetic continuity with the existing arid-themed plantings around our Arid Green-house, which adjoins the entrance. The worldwide planting palette was drawn from subtropical, desert, and temperate mediterranean environments that were unified by their tolerance for drought. This unique mix of subtropical and arid climate plants we have come to call “arid-exotica.”

A hybrid Comarostaphylos from Mesoamerica. Photograph by Janet Williams

A hybrid Comarostaphylos from Mesoamerica. Photograph by Janet Williams

Starting with the specimen trees and massive glazed pots used in the garden show, we began to lay out the plants in the new garden. With three or four pairs of eyes looking over every plant placement, the process was one of trial and error. Many elements had to be moved several times. Textural combinations of spiky cycads, palms, and succulents contrasted with soft and flowing grasses and sedges drawn from Mexico, New Zealand, Argentina, Chile, and California. Color combinations tended toward blues and grays contrasting with soft ochre, orange, and yellow. Many other interesting shrubs, perennials, geophytes, and ground covers were used as well.

Dominant plants in the scheme include large specimens of palo verde (Parkinsonia aculeata) that flank the stairway to the oval patio, marking the descent into the garden and framing the view out into the Mesoamerican and Californian sections. Large plants with strap shaped leaves, such as Dasylirion quadrangulatum, Yucca rostrata, and Nolina nelsoni, filled out the rest of the planting, providing both drama and structure.

More containers offer specialized soil conditions for selected specimen plants, such as the hybrid Comarostaphylos in the glazed urn

More containers offer specialized soil conditions for selected specimen plants, such as the hybrid Comarostaphylos in the glazed urn

The glazed containers provided color and textural contrast while highlighting specimen plants. Unusual container features include a swollen-based, delicately blue-foliaged Euca-lyptus orbifolia, a pink-suffused, red-flowering hybrid Mesoamerican Comarostaphylis, and a rare palm (Brahea brandegei) from Mexico.

Mature specimens of several rare and striking cycads (Encephalartos spp.) were used throughout the planting. Some of the featured cycads have a naturally narrow distribution; habitat destruction and pillaging by zealous illegal plant collectors have earned them a prominent place on the IUCN’s “Red List” of plants threatened with global extinction. As the conservation of plant biodiversity is central to UCBG’s mission, we are preserving these plants in cultivation and hoping to reduce some of the pressure on wild populations through propagation and global exchange of pollen. Showcasing these plants gives us the opportunity to educate visitors about the importance of plant conservation. While in-situ preservation is clearly the preferred approach of conservation biologists, in these times of increasing environmental pressure, the utility of germ plasm preservation cannot be overlooked. The entry planting includes some relatively common plants as well as a suite of unusual plants that deserve broader use. Anthony, in particular, has been enthusiastic about dwarf selections of Beschorneria that could become more utilized in future landscapes. The final aesthetic and functional touch was the three-color aggregate gravel mulch that helped tie the planting design together by linking the paving with the rockwork.

The view through UCBG’s new gate to the Entry Garden and the Arid Greenhouse beyond

The view through UCBG’s new gate to the Entry Garden and the Arid Greenhouse beyond

Planting the Future

For the future of this particular garden, and gardens in general, we must carefully consider environmental suitability, sustainability, and the use of the water. We hope to expand the public’s concept of arid-climate gardening by drawing from a worldwide plant palette, including items of subtropical origin such as the dry-growing bromeliads (Abromeitielia, Puya and Hechtia), Beschorneria, Bocconia, and bamboos such as Otatea. Even a tropical look can be achieved in a water-thrifty garden. With the experience gained from growing the 13,000 different taxa at UCBG, we are in a unique position to broaden the public’s understanding of regionally appropriate plants for the West Coast and beyond.

Even regionally appropriate plants, however, require some irrigation, particularly in the establishment phase. With an eye toward conservation, we designed a water-efficient irrigation system using micro-spray emitters and a state-of-the-art controller. The controller is linked to an on-site weather station; technical service is provided by ET Water. The system calculates daily evapo-transpiration rates, and considers other factors, such as plant type, slope, and soil type, and then adjusts the irrigation accordingly, thus reducing waste. The micro-spray irrigation system provides thorough coverage and flexibility, while minimizing evaporation and runoff, and offers relative ease of maintenance.

Sustainability of the entry garden with its unique flora is linked to the financial sustainability of the entire botanical garden, which relies on continuing public support in the form of memberships, gifts, and visitor entrance fees. The new entrance was wholly funded by gifts from supporters. We hope you will come enjoy the new entrance, visit the garden, and support our mission as we continue to sustain a diverse living collection of plants that fosters teaching and worldwide research in plant biology, furthers the conservation of plant diversity, and promotes public understanding and appreciation of plants and the natural environment.

An assortment of containers embellish the Entry Garden in this view towards the California Native Garden

An assortment of containers embellish the Entry Garden in this view towards the California Native Garden

If You Should Like to Visit . . .

The University of California Botanical Garden is located at 200 Centennial Drive in Strawberry Canyon, above the football stadium on the Berkeley campus. The garden is open daily except Christmas and other holidays, from 9 am to 5 pm. Admission is $5, seniors $3, children $1; admission is free on the first Thursday of every month. There is a parking fee. For information about the collection, educational programs, membership, and volunteer activities call 510/643-2755 or visit http://botanicalgarden.berkeley.edu.