Designing Gardens with California Natives

This is a great reference for designing beautiful, ecological gardens, using a plant community approach. The book focuses on California native plant communities (plants that grow together because of similar adaptations), including bluffs and cliffs, redwood forest, desert gardens, montane meadows, mixed evergreen forest, oak woodlands, grasslands, chaparral, riparian woodlands, and wetlands. The authors are Glenn Keator and Alrie Middlebrook; the publisher is University of California Press.

For each garden design, the authors provide a unique representation of the garden plan, practical project information, descriptions of plants and the plant community, and information about places to visit to see the plant community in nature. The resource section provides a comprehensive list of native plant sources, books, botanical gardens and arboreta, public gardens, websites, and a seasonal calendar for managing native gardens.

Glenn Keator is a botanist, author, and lecturer with extensive knowledge of California native plants. I’ve had the pleasure of taking his Mediterranean plant ID class at Merritt College. Alrie Middlebrook founded Middlebrook Gardens in San Jose, which specializes in designing California native gardens, and is also an author and lecturer. I was intrigued by her use of succession (moving through a series of simple-to-complex planting stages, culminating in a final stage) in her garden designs.

Sudden Oak Death

For the past twenty years, oaks in Northern California have been under siege from a plant pathogen called Phytophthora ramorum, commonly referred to as Sudden Oak Death (SOD). P. ramorum produces spores that are dispersed through the air or water, or carried by people, animals, plants, soil, and equipment. The ideal condition for P. ramorum is warm (68 degrees) and moist, making riparian woodlands especially susceptible. Coastal counties from Humboldt to Monterey have been especially hard hit.

Forest near Big Sur, California showing symptoms of Sudden Oak Death.
Photo by Hemhem20X6 (released into the public domain, by the author),

Symptoms include cankers on the trunk or limbs of a tree; and rapid leaf or canopy death over a two to three week period. Quercus agrifolia and Q. kelloggii oaks have a high mortality rate. Other woody plants in the plant community may be hosts to the disease—including rhododendron, California bay laurel, madrone, Manzanita, redwood, coffeeberry, and California buckeye. The pathogen is not native, and may have been introduced through an imported ornamental plant, possibly from Asia. So far there is no known cure; infestations should be reported for diagnosis, since other diseases have similar symptoms.

The California Oak Mortality Task Force was assembled in 2000 to address the pathogen and its affects, and to coordinate with other agencies, universities, and other private and public groups. Several websites provide information: http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74151.html, www.suddenoakdeath.org, and www.na.fs.fed.us/SOD.

Caring for Oaks

In nature, oak trees can live 350 to 500 years, well over the human lifespan. They grow through several stages – seedling, juvenile (2-5 years), adolescence (15 – 50 years), maturity (50 – 200 years), and senescence (200 plus years) – as they form their particular shape and character. Oak trees require space and have particular soil, watering, and nutrition requirements. Caring for oaks in the garden requires basic understanding of these needs, and a vision that extends beyond the gardener’s own lifespan:

A Quercus agrifolia seedling. This acorn was most likely
"planted" by a squirrel in preparation for winter.

• Seedlings require lots of water to become established. This may mean deep, weekly watering (15 gallons) for the first two years.
• Once established, oaks require much less watering. Many California native oak species are adapted to the summer-dry climate. After three years, they should not be watered in summer, except during extreme or prolonged drought.
• Oaks establish a deep tap root, as well as many shallow feeder roots at the surface within the drip line. These feeder roots should not receive any direct water, to avoid root rot. This means clearing away lawn or plants under the oak.
• If you do plant under an oak, select species with compatible water needs, preferably within its natural plant community.
• Protect oak roots during construction projects. Problems may manifest in an oak tree long after the project is completed if roots are damaged during construction.
• Mulch with the oak’s own organic matter (fallen leaves, acorns, and catkins), up to, but not touching, the trunk. Do not use other fertilizers.
• Prune toward the end of summer, when the weather is still dry, since oaks seem to be susceptible to water borne pathogens. Work with an arborist to develop a strong limb structure through pruning, while the tree is young.

Urban oaks face continual menace from damage, overwatering, space constraints, improper pruning, and disease. With some care, they can live into maturity, giving pleasure to people, and providing habitat for birds, insects, and wild life.

Fall is in the Air

It may be difficult to tell when fall comes to the San Francisco Bay Area, especially if you are from a region of the country where seasons are very distinct. In the Bay Area the change is more subtle – plants have a spent, dehydrated look, the hills are golden brown, leaves turn brown and wither, different types of flowers bloom, dry-deciduous trees drop some leaves to conserve water after several months without rain.

But to the seasoned Bay Area resident, the air does seem different as fall approaches. The days grow shorter. On the coast, the air is a crisp 60-70 degrees; inland it is typically closer to 90 degrees. The fog lingers in the trees and sheltered canyons a little longer in the morning, and rolls in as a high wall in the evening. Grasses and late-blooming flowers go to seed. The garden continues to produce lettuce, beans, peas, and tomatoes, but the leaves start looking weathered and a bit mildewed. Liquid Amber leaves start turning gold and red. Fall is here.

In fall, the Crape Myrtle blooms with vibrant
purple, rose, and crimson blossoms.

Oaks in California

Several species of oak are native to California. I have been trying to learn more about them, and learn how to identify them. Identification is still tricky; some species are distinctive, others seem very similar to each other. Here are a few native oaks that I’m learning to recognize:

• Quercus agrifolia – also called Coastal Live Oak, California Live Oak, and California Field Oak. This evergreen tree thrives in coastal conditions, within 50 miles of the ocean, and in a forest setting. Leaves are slightly elliptical, 1-2 inches long, glossy dark green on the upper side, and serrated. Bark is smooth and dark gray. Male flowers are catkins; female flowers are flowered spikes. The cap of the acorn encloses 1/4 to 1/3 of the nut. Trees can reach 70 feet in height.
• Q. chrysolepsis – also called Canyon Live Oak, and Canyon Oak. This evergreen tree is native to foothills, mountain slopes, and canyons. Its range is the entire length of California, from sea level to 9,000 feet. Yosemite has groves of Canyon Oak. Leaves are elliptical, 1-4 inches long, glossy green on the upper side and grayish and felt-like underneath, serrated when young, then smooth when old. Bark is pale gray and furrowed. Flowers are similar to Q. agrifolia. The cap of the acorn encloses 1/4 of the nut, and the acorn is small and egg-shaped. Trees can reach 60 feet in height.
  
• Q. garryana – also called Garry Oak and Oregon Oak. This deciduous tree thrives from British Columbia to the Santa Cruz Mountains in California. Leaves are lobed, 3-6 inches long, dark green glossy above (turning reddish brown in fall), and downy underneath. Bark is gray, scaly, and checkered. Flowers are similar to Q. agrifolia. The cap of the acorn encloses 1/3 of the nut. Trees can reach 90 feet in height.
  
• Q. kelloggii – also called California Black Oak and Kellogg Oak. This deciduous tree thrives in the foothills of the Sierra Nevada and in the Coast Ranges, but away from the coast. Leaves are oblong, to 6 inches long, divided into dentate lobes, glossy green above (turning to yellow or yellow orange in the fall), and pubescent underneath. Bark is dark, furrowed, and checkered. Flowers are catkins. The cap of the acorn encloses 1/3 to 1/2 of the nut or more. Native people groups used the acorn as a staple food. Trees can reach 80 feet or more in height.
  
• Q. lobata – also called Valley Oak, California White Oak, and White Oak. This deciduous tree is native to California’s Central Valley and foothills away from coastal influences. It prefers rich, well-watered bottom land. Leaves are deeply lobed, 3-4 inches long, dark green above and paler gray-green and felt-like underneath. Flowers are catkins. The cap of the acorn encloses 1/4 of the nut, and the acorn is elongated. Native people groups used the acorn as a staple food. Trees can reach 80 feet in height.

Q. lobata at The Ruth Bancroft Garden is 350 years old.

Q. lobata leaves are lobed. Leaf shape, bark, flowers, and fruits are used collectively to identify a tree.

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These descriptions have been compiled from: Hortus Third (Bailey), Plant Life in the World’s Mediterranean Climates (Dallman), and The Western Garden Book (Sunset).

Quercus – Fine Trees

Oak trees are quintessential California. The image of a massive oak set apart on a rolling, golden hill is iconic. In California, oaks appear in the landscape from the foggy coast, to chaparral canyons, to the hot Central Valley, to the hills and foothills of the Sierras. Each type is especially adapted to the soil and microclimate of the area.

Oak woodland in Sonoma County

Oak trees are categorized in the Fagaceae family, in the Quercus genus. The origin of the Latin word quercus is thought to be derived from the Celtic for “fine” and “tree”. Within Quercus are about 500 species. Some are deciduous (drop their leaves) and others are evergreen. Some of the evergreens are summer- or drought-deciduous, meaning they drop some leaves during the dry season or drought as a water conserving strategy. The common name “live oak” refers to evergreen oaks.

Graceful limbs of Quercus agrifolia close to the coast

Leaves may be lobed or serrated (little teeth); flowers are catkins (slim, cylindrical flower clusters), and the fruit is the acorn. They are long-lived; some may grow to be 350 – 400 years old with the right conditions. Some species thrive in a forest setting, others require lots of space and deep soil. Oak trees may be host to many birds, animals, and insects, making them an important part of the environment.

Natural Raised Beds

Many desert and Mediterranean plants can live in nutrient poor soil, but most of them require great drainage. I have observed this in my desert travels, where the soil is very rocky and porous, and the terrain is frequently a sloping plain. These plants do not like wet feet! This presents a problem if you are growing a dry garden in the San Francisco Bay Area, where the soil is wet, heavy, and often nutrient rich.

California native plants on a raised berm.

The Ruth Bancroft Garden met this challenge by importing crushed rock from Mount Diablo, and creating large berms or mounds for their planting areas. These natural raised beds provide good drainage for the dry garden. They have also amended the heavy alluvial soil with organic matter to create lighter, more porous soil.

Cacti planted on a raised mound.

This technique of creating berms or mounds for dry gardens can be adapted for the home garden. On a small scale, a container, such as a clay pot, can be incorporated into the garden design to provide good drainage for dry-loving plants.

Shady Ideas

The Ruth Bancroft Garden in Walnut Creek implements an extensive arbor (or pergola) to incorporate shade into the garden design. Planted under the arbor is a succulent border, reminiscent of an English border garden, but with the water conserving plants of desert and Mediterranean climates. Besides providing shade for the plants, the structure seems to cool the air in close proximity, and capture any passing breeze.

The arbor provides shade for the succulant border.

The arbor is a simple wood frame, covered with shade cloth, which is available at garden supply and hardware stores, and on the web (for example, Coolaroo sells shade cloth by the yard: http://www.coolaroousa.com/).

The arbor is constructed of a wooden frame and shade cloth.

This is a wonderful, practical idea for gardens in hot, dry climates, and could easily be adapted on a smaller scale for the home garden. This is also a great example of adapting a garden style, in this case the English border garden, to the local climate or microclimate.

The Ruth Bancroft Garden

Admittedly, visiting a dry, prickly garden in Walnut Creek in the heat of day at the height of summer does not sound that appealing. But I love the desert ecosystem and went anyway. I’m glad I did. The Ruth Bancroft Garden is well established with the perfect combination of trees for shade, a water treatment, and artful beds of succulents, cacti, and Mediterranean plants from all over the world. On the afternoon I visited, there was a continual breeze, lots of shade, and very pleasant. I was surprised to see some plants in bloom, including agave, cacti, and several varieties of trees and bushes. The air hummed with the activities of bees, butterflies, and birds.

Ruth's Folley - houses small store and greenhouse.

Ruth Bancroft started collecting succulents in the 1950s; in 1972 she worked with Lester Hawkins of Western Hills Nursery in Occidental, CA to design the dry garden in Walnut Creek. The three-acre parcel was originally part of the 400 acres of native oak trees that Hubert Howe Bancroft cleared in the 1880s for a fruit and walnut orchard. The garden design is a series of paths and garden beds planted with Ruth’s collection.

The pond forms a focal point for the garden.

The garden has a primitive, primal feel to it – I almost expected a dinosaur to appear around a bed of wild looking plants, or to come swooping in from an opening in the tree canopy. This amused me, but I think it expresses the feeling the garden conveys. Many of the plants are monocots – ancient plants, with simple (but amazing) strategies for conserving water and reproducing. I enjoyed my self-guided tour, but plan to return for a docent-guided tour to learn more about the plants, and the garden design. To learn more: http://www.ruthbancroftgarden.org/.

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Sonoma Land Trust

In 1984, Otto and Anne Teller, owners of Oak Hill Farm, donated a conservation easement to the Sonoma Land Trust, of which they were founding members. A conservation easement is a voluntary legal agreement between a private landowner and the Land Trust to “preserve in perpetuity the conservation values of the specific land they cover.” In this case, the conservation easement protects the productive agricultural land of Oak Hill Farm, as well as the oak and manzanita woodland. The 700-acre Oak Hill farm property will remain as it is for generations to come.

The Sonoma Land Trust was formed in 1976, to preserve open land in Sonoma County, before it was completely developed for housing and business. The Land Trust provides stewardship for other agricultural properties, such as Glen Oaks Ranch, as well as open spaces and wild life corridors, such as the Jenner Headlands and Secret Pastures.

Oak Hill Farm and the forested hill beyond are protected

I appreciate this vision of preserving farms and open land, and providing stewardship. Open land provides a psychological reprieve from the congestion and demands of our busy, over-crowded lives. It also helps ensure some space for wild life, natural systems, and hope for the future. Surely we have enough strip malls and cement sprawl in place, so that we can preserve some open and wild land for all to enjoy.

Red Barn Store at Oak Hill Farm

After touring Oak Hill Farm, I shopped at the Red Barn Store. What a treat to step into the cool store after being in the midday sun, and to be met with the intense fragrance of real produce. And how satisfying to see the produce I’d seen in the fields now washed up and presented on the shelves like pieces of art, and ready to be taken home to create flavorful and nutritious meals. Herbs, berries, watermelon, peppers, chard, eggplant, carrots, flowers and bouquets, squash, cucumbers, to name a few, beckoned from the shelves.

Eggplant	Apples
Peppers	Berries

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The Red Barn Store was handling a continual stream of customers. I did my part to contribute. Some of my purchases included a beautiful sunflower bouquet, an assortment of heirloom tomatoes, a bunch of aromatic basil, olive oil (grown and pressed by Lucero Olive Oil with the Oak Hill Farm label), intensely fragrant apples for pie or apple sauce, and fingerling potatoes that look like ginger root and have a wonderful earthy smell. I would have purchased more, but there are only two of us at home now that our son is back to college.

Now I’m ready to make the kitchen smell good with all these fresh, beautiful ingredients, and the lettuce, peas, parsley, and tomatoes from my own little raised bed. Bon appétit!

Oak Hill Farm

I spent a fabulous morning touring Oak Hill Farm in Sonoma County. About 15 of us gathered at the Red Barn off Sonoma Highway at 10:00 a.m., then David Cooper, the farm manager, lead us on a tour of the historic farm’s barn, greenhouse, orchard, and fields. Cooper has degrees in chemical engineering, but decided being stuck in an office was not for him. He's been a farm manager for about four years now.

David Cooper leads the tour	Beehives on the hill
Basil, melon, sweet potato, squash	The barn

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The farm is beautifully situated – surrounded with oak and mixed evergreen forest. We learned about the farm’s organic and sustainable farming methods, which have been in place since the 1950s when the owners purchased the farm. They grow a whole array of fruits and vegetables, rather than planting a single crop. They practice crop rotation, plant cover crops to enrich and protect the soil between plantings, and allow a beekeeper to keep beehives on the property (honey for him, pollinators for Oak Hill Farm). The property is alive with bees and birds (and gets its share of pests in the form of deer, crows, squirrels, and gophers).

The produce is sold directly to several restaurants in San Francisco, at Farmers’ Markets (Ferry Terminal and Jack London Village), through CSA subscriptions, and at the Red Barn on the property. The tour is offered the first Saturday of the month. It is a great opportunity to see a farm in operation, and spend some time surrounded by beauty, growing things, and the natural world. To learn more: http://www.oakhillfarm.net/.

Planning a Farm Trail Adventure

I love an expedition, and Sonoma County Farm Trails offers eight of them. Download their Map and Guide PDF from the Farm Trails web site, and start planning: http://www.farmtrails.org/map-guide/. Pick a region, pick a vendor, or pick a product, and go from there.

The Sonoma Valley region looks inviting (and close – around 56 miles from us). It is also known as  the Valley of the Moon, and is close to the ruins of Jack London’s Wolf House. I see several interesting options – an alpaca ranch, several wineries, a farm that offers a tour the first Saturday of the month, another farm that sells heirloom tomatoes at a roadside stand, and an artisan cheese manufacturer.

Goat herd resting in the heat of the day

Searching through the vendor descriptions, I learn more about what they offer – weaving and spinning supplies, CSA subscriptions, puppies, farm stays, eggs, herbs, honey, wreathes, soap, and so on. I could easily shop for the week, and start my Christmas shopping early. And this is just one of the eight regions!