About the Garden

The mission of Sonoma Botanical Garden is to inspire an appreciation and understanding of the beauty and value of Asian and California native plants, and to promote their conservation in natural habitats and gardens.


Jane Davenport Jansen, Founder


Inspired by Jane's vision, passion, and unending support, the Sonoma Botanical Garden is a globally recognized botanical garden, planted from seed in the remains of an abandoned quarry in the fertile Sonoma Valley which celebrates Asian and California native plants.

A fast moving fire swept through the foothills of the Mayacamas Mountains of eastern Sonoma County in 1964, burning almost everything to the ground. The following year, Knobcone Pine seedlings quickly sprouted in the ash-covered, rocky soil and shoots sprang from the remains of the charred madrones. Gradually, much of the range became a dense scrubland as California hillsides often do after great disturbances.

In 1968, Jane Davenport Jansen purchased more than 40-acres northeast of Glen Ellen in the Mayacamas foothills, and two years later planted cabernet vineyards on the open valley floor. 

At that time and continuing through the early 1970s, the global landscape was redefining the relationship between the United States and China. Borders began to open and by the 1980s California nurseries had a steady inflow of new and exotic decorative plants that sparked the interest of landscape designers and home gardeners alike.

Simultaneously, China was rapidly expanding and industrializing to meet the demands of its population and growing global economy, which - as is the story with human development anywhere - meant the sudden and exponential loss of natural areas, increase in habitat fragmentation, and decline of some of the richest temperate flora on earth. 

The birth of the Garden was a combination of Jane's curiosity and this unique global opportunity. With the introduction of Asian species to the horticultural trade, the need for botanical documentation of their at-risk wild counterparts, and the means to create a safe-haven for this exotic flora, Jane pursued her love and fascination through partnerships with the Royal Botanic Garden, Kew, and the Howick Arboretum.

In 1987/1988, she was able to facilitate the first collecting expeditions to Japan and China. William McNamara was hired as a landscaper at that time and accompanied horticulturists from partner gardens throughout the years in search of plants for research, conservation, and collection. He later became the Garden's Executive Director and retired after 32 years in October 2019.

The nursery was established on site in 1988, and by the spring of 1990 young plants grown from the wild-collected seed were ready to be planted on the 22-acres of rocky, steep hillsides above the vineyards. 

The remains of several abandoned sandstone quarries which had been mined for road base provided a unique terrain that lent itself to further enhancement. The large man-made ponds and meandering streambeds that wind through the Garden today were built to enhance the existing geology and compliment the Asian woodland garden. This topography also inspired Jane to name the property Quarryhill Botanical Garden. The Garden was born and open for private tours with a mission to conserve wild Asian species by providing living specimens and herbarium vouchers to the global scientific community as well as being a memorable woodland garden for those, like Jane, who have never been able to visit the wild woodlands of East Asia in person.

Annual collecting expeditions to East Asian with McNamara and others continued through 2017. These seeds were regularly grown, tended, and planted out to continue to fill in the unique botanical garden. Oaks, maples, magnolias, dogwoods, lilies and roses are particularly well-represented in the Garden. Today, the Garden is home to one of the largest collections of scientifically documented, wild-source Asian plants in North America and Europe, many of which represent ancestors of horticultural favorites.

Rooted in a love for wild biodiversity and conservation, the Garden continues to evolve with a particular focus on rare and endangered plants. In 2021, the Garden naturally progressed to turn its gaze closer to home and another biodiversity hotspot - California. With similar catastrophic habitat loss and fragmentation from urban sprawl, road construction, and introduced species, California's native flora is facing some of the same biodiversity challenges Jane and her colleagues began to combat in the 1980s.

Added to the Garden in 1998, the Three Springs Ranch property vastly increased the Garden's potential for environmental education, yet thus far this 22-acre parcel of native oak savannah and chaparral has been mostly concealed from public view. In this property the Garden sees another opportunity to celebrate and conserve both plant and animal species found closer to home, and to bring its horticultural skills to the cultivation of California native plants as well as Asian species. On top of a multitude of unique species, California is home to some of the same genera that are quintessential to East Asia (maples, roses, rhododendrons, oaks, and more). This complementary direction gives the Garden the unique opportunity to tie together local focus, regional impact, and global relevance.

"Adapting our mission to include California botany will allow us to be even more sensitive to wildlife, water, and wildfire issues that are so present in our community and the world at large. We hope that encountering specimens of California's endangered native flora will lead people to an appreciation of plant-conservation challenges around the world, including those found in Asia, and vice versa - that learning about the endangered flora of Asia might inspire local action to save California plants," said Scot Medbury, Executive Director at Sonoma Botanical Garden. 

With this revised mission, a new name was needed to encompass the whole of the Garden - Asian woodland and Three Springs Ranch. Quarryhill Botanical Garden became Sonoma Botanical Garden. "We anticipate that the new name and enhanced mission will strengthen the Garden's connection to our community, advancing our environmental-education impact in an era of climate change," said Jerry Newell, Chair of the Garden's Board of Directors.

Jane worked tirelessly until her death in 2000, personally funding the entire operation and generously supporting fifteen expeditions. The Garden continues to thrive and honor her by operating an excellent botanical garden and adapting to the changing needs of Sonoma Valley and the scientific community at large. The 'easy loop' that encircles the hilltop in the historic core of the Garden has been renamed the Quarryhill Loop to tell the story of the Garden's history.