The Ruth Bancroft Garden where plants from all over the world are welcome

The Ruth Bancroft Garden in Walnut Creek, California, is a 3-acre remnant of a 400-acre fruit farm started in the 1880s by Hubert Howe Bancroft.  Bancroft is a familiar name in the Bay Area because Mr. Bancroft was also a famous historian and publisher who amassed a huge collection of documents about the American West.  He donated that collection to University of California at Berkeley, which is the origin of the Bancroft Library there.  The Bancroft Library is California’s greatest repository of California history.

When Mr. Bancroft purchased his property, it was oak woodland.  These were the venerable valley oaks (Quercus lobata), the largest oak in Northern California.  Only one of these oaks remains in the garden.  It is estimated to be 350 years old.  Its contorted branches create an enormous tent of shade, reaching to the ground.  There is not a more beautiful tree, in our opinion.

Mr. Bancroft’s granddaughter-in-law, Ruth Bancroft started planting her garden in 1972.  She had a life-long interest in cactus and succulents, so it wasn’t a good year to begin that venture. The hard freeze of the winter of 1972-73 killed many of the young plants which are not hardy in temperatures below freezing.  Fortunately, such hard freezes are rare in the Bay Area and the garden has suffered significant losses only once since then, in winter 1990.

There are several eucalyptus trees in the garden, but one is a stand-out.  The ghost gum (Eucalyptus pauciflora) is aptly named for its white bark.  Coincidentally its ancestral home is the Snowy Mountains in Australia where it is often found standing in the snow.  It is one of the few cold-tolerant species of eucalypts.  Our opinions of eucalypts are heavily influenced by one particular species, the blue gum eucalyptus, because it is the predominant eucalypt in California.  We often forget that there are actually 700 species of eucalyptus and therefore there are a wide variety of forms and horticultural characteristics.  The ghost gum in the Bancroft Garden was flowering and swarming with bees collecting pollen and/or nectar.  The flowers were close to the ground so we were able to confirm that the nectar was not at all sticky, as critics of eucalyptus often claim.

Touring the garden, we were reminded of many of the themes of the Million Trees blog.

Planting species outside of their range is insurance

The plants in the Bancroft Garden are from all over the world, particularly similar climates such as Australia, South Africa, and Mediterranean countries.  Many of the plants come from drier desert climates.  Several of the plants in the garden are extinct or nearly so in their native ranges.  They continue to exist in the world only because they were exported to new locations before they disappeared from their ancestral homes. 

This is one of many reasons why we do not share the purist vision of the native plant movement, that only plants native to a particular location be allowed to exist in that location.  In a changing climate, it is particularly important that plants and animals be allowed to remain where they have been introduced.  Their new homes are insurance against their extinction from the Earth.

The characteristics that native and non-native plants have in common

Although most of the plants in the Bancroft Garden are not native to California, there is a section of the garden that is devoted to native plants.  Ruth Bancroft had some difficulty establishing that portion of the garden:  “When Ruth Bancroft decided to experiment with native California penstemons…many of her plants died.  She added even more rock to the bed and planted again.  In the improved drainage, that this rocky bed now provides, penstemons thrive alongside such other California native perennials as woolly blue curls and…buckwheats.”

Matilija poppy (Romneya coultera), is another California native in the Bancroft garden, but one which must be watched closely because, “…its major problem is that it spreads underground and can be invasive.”   This is a description often applied to non-native plants.  However, when the author is a horticulturalist, rather than a nativist, it is sometimes applied to native plants as well.

There is also a native Manzanita in the garden which is a hybrid descendent of two unrelated Manzanita species which have long since disappeared from the garden.  Hybrids of native plants are often eradicated by native plant advocates who want to freeze all native species into place.  Hybridization represents change and abhorrence of change is a basic tenet of nativism.  The existence of this hybrid in the Bancroft Garden is an example of why we are opposed to nativism in its purest form.  The hybrid survives, but its two ancestors are gone.  Aren’t we better off with this survivor in the Bancroft Garden than with no Manzanita at all?

The Bancroft Garden was an opportunity to revisit these themes of the Million Trees blog:

• Native plants are as likely as non-native plants to require tending in the garden, such as soil amendments
• Both native and non-native plants are sometimes invasive
• Hybridization is another means of insuring the survival of plant genes

This is a particularly good time to visit the Bancroft Garden.  There is an exhibit of sculpture by artists from all over the West Coast in the garden until July 14, 2012.  It is an interesting and lovely garden which is rich in California history.