Wildlife Gardening in the Central Valley

By: Ellen Zagory Diane Cary

Ellen Zagory is director of horticulture at the UC Davis Arboretum, where she frequently lectures on bringing wildlife into the…

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Diane Cary is communications director at the UC Davis Arboretum, a researcher in the Landscape Architecture program at UC Davis,…

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California pipevine swallowtail butterfly (Battus philenon). Photograph by TW Davies, courtesy www.calphoto.com

California pipevine swallowtail butterfly (Battus philenon). Photograph by TW Davies, courtesy www.calphoto.com

Recent evidence that birds, butterflies, and native ecosystems are on the decline has resulted in an increased interest in “wildlife gardening”— creating gardens that can better support wild creatures. Gardeners sometimes use the word “wildlife” in a narrow fashion; not many would be happy to have deer, skunks, coyotes, or mountain lions prowling their backyard retreat, but many other creatures are wonderful additions to the garden. Wildlife gardening, also called habitat gardening, generally refers to creating gardens with plant associations and vegetation communities that are inviting to birds and beneficial insects. In this new paradigm, our gardens are not just for human pleasure and food production. Gardens and urban landscapes can supply the food, water, and shelter that wild lands and fallow fields once provided for these creatures.

A search of the Internet (see For Further Reading, page 22) will uncover all the information you need on the general principles of creating a wildlife habitat garden. It is important to include at least some locally native plant species, since native creatures have evolved with native plants. But a wildlife habitat garden does not have to consist exclusively of native plants. Emerging evidence shows that less specialized insects also visit introduced (non-native) garden plants. We have found that plants from the world’s mediterranean climate zones, as well as from other hot-summer areas like Mexico and the American Southwest, can be successfully combined to create beautiful and wildlife-supporting Central Valley gardens.

California pipevine (Aristolochia californica), host plant for the pipevine swallowtail butterfly. Photographs by Ellen Zagory, except as noted

California pipevine (Aristolochia californica), host plant for the pipevine swallowtail butterfly. Photographs by Ellen Zagory, except as noted

Plants that Attract Beneficial Insects

Beneficial insects are those that help our gardens grow by pollinating plants and helping to control insect pests. They include the many bees, butterflies, and moths important for pollination of food crops, ornamental plants, and wild plants. Hoverflies, lacewings, many beetles, and predatory wasps are beneficial because they eat insect pests. Parasitic wasps, sometimes too tiny to see, are common in our area and help control aphid outbreaks by injecting their eggs into the aphid body, eventually killing the aphid host.

Beneficial insects are attracted to plants that provide copious and easily accessible pollen and nectar. Some perennial pollen and nectar plants that we have found to be attractive and adaptable in the Central Valley are goldenrod (Solidago californica Cascade Creek form), seaside daisy (Erigeron glaucus ‘Wayne Roderick’), the many forms of yarrow (Achillea millefolium), and red buckwheat (Eriogonum grande var. rubescens). Among the woody shrubs, some of the most tolerant of our conditions are toyon (Heteromeles arbutifolia), hairyleafed coffeeberry (Rhamnus tomentella), larger forms of buckwheat such as E. giganteum and E. fasciculatum, and a number of California lilacs, especially Ceanothus maritimus ‘Valley Violet’, C. arboreus, C. ‘Ray Hartman’, C. ‘Concha’ and C. ‘Gentian Plume’.

Autumn sage (Salvia greggii)

Autumn sage (Salvia greggii)

Butterfly Plants

To increase the habitat value of your landscape, and to provide for movement and color in the summer garden, include plantings of favorite butterfly plants. Before installing a Central Valley butterfly planting, be sure to visit Art Shapiro’s Butterfly Site (see page 22) for up-to-date information on butterflies of the region.

While many plants that are useful to beneficial insects are also visited by butterflies, some flower too early in the Central Valley to coincide with the summer and fall flight periods of most butterflies. The summer-blooming natives listed above (Erigeron, Solidago, Achillea, Eriogonum) are useful for attracting butterflies. Some good generalist nectar providers also include later-blooming, non-native species. Perennial sedums, such as Sedum ‘Herbst-freude’, are excellent for attracting a number of different butterflies in summer. Ornamental oreganos, like Origanum ‘Ray Williams’, O. ‘Santa Cruz’, O. ‘Hopleys’, and O. ‘Betty Rollins’, are butterfly favorites. Lavenders also provide nectar. For late summer and fall, asters of many kinds are useful; one favorite is Aster ‘Purple Dome’, whose bloom can be delayed by cutting the plants back in July. The vigorous native A. chilensis could also be used, but its rapid spread limits its usefulness to large, nonirrigated areas.

Habitat gardens should also provide food for the larval (caterpillar) stage of our native butter-flies. Many important larval food sources are species we think of as weedy, such as alkali mallow (Sida hederacea), plantain (Plantago sp.), turkey mullein (Eremocarpus setigerus), fennel (Foeniculum vulgare), and Lotus species. In our gardens, milkweeds (Asclepias spp.) provide food for monarch butterfly larvae as well as nectar for a wide variety of butterflies. Gardeners who live within a mile or so of a natural waterway and plant the California pipevine (Aristolochia californica), the only larval food of the California pipevine swallowtail, are likely to be rewarded with a late winter or early spring hatch of these big, beautiful, iridescent purple black butterflies.

Hummingbird Plants

One of the easiest creatures to attract to a Central Valley garden is Anna’s hummingbird, a nearly year-round resident. This lively and assertive bird will entertain you daily. Hummingbirds love sages (Salvia spp.); both native and non-native sages will make a hummer happy. One favorite is the native hummingbird sage (Salvia spathacea), which flowers from late spring into summer. For a fall nectar supply, use selected forms of California fuchsia (Epilobium canum, syn. Zauschneria californica) such as the dwarf ‘Everett’s Choice’, which spreads slowly. Narrow-leafed, upright forms with green leaves, such as ‘Bowman’s Best’, also put on a good show without too much spread. The vigorous silverleafed ‘UC Berkeley Hybrid’ and ‘Catalina’ should be restricted to areas where they won’t overwhelm other plants. (See also page 42.) Chaparral currant (Ribes malvaceum), which flowers from November through January, and manzanitas like Arcto-staphylos densiflora ‘Howard McMinn’ and A. pajaroensis that bloom in January and February will provide winter nectar for hummingbirds.

Trees and Shrubs for Birds

According to recent work reported in The Garden, a publication of the Royal Horticultural Society, the most important element for increasing biodiversity in the garden is the presence of large trees. If your garden has space, planting a shade tree will not only cool you in summer but also provide food for insecteating birds, and habitat for nesting and raising their young. Large trees provide niches for birds with different feeding habits, such as bark gleaners (creepers and nuthatches), leaf gleaners (warblers), and wood and bark probers (woodpeckers). California’s native oaks—in our area, valley oak (Quercus lobata)—are the keystone plants of our native communities, providing a wealth of food, shelter, and nesting sites. Acorn woodpeckers, scrub jays, nuthatches, and mourning doves feed on acorns and the insects attracted to them. Large trees like pines (Pinus spp.), sycamores (Platanus spp.), and poplars (Populus spp.) also provide seed and roosting sites.

Some of the same native shrubs that support beneficial insects in spring, like native roses, toyon, and elderberry (Sambucus spp.), also provide fruits for birds in fall. Leaving a tangle of shrubs as a thicket along with a strategically placed bird feeder attracts many kinds of birds, among them white- and golden-crowned sparrows, dark-eyed juncos, and orange-crowned warblers. The safety of the thicket provides them with cover from which they can dash out for water and seed and make a quick retreat if threatened.

The Central Valley’s population is expected to exceed forty-six million people by 2030—an increase of ten million above current levels. The drastic loss of habitat that this growth portends could be partially offset if the landscapes of new homes and businesses were designed to support wildlife, and if roads and highways were planted with stable matrices of native grasses and herbs able to stand up to weedy invasive plants. We have the opportunity to create patches of habitat in our gardens and community landscapes to provide wildlife corridors between larger natural areas, thus allowing native birds and insects to continue their age-old patterns of migration, and ensuring a more diverse and stable environmental future for us all.

Blue grama grass (Bouteloua gracilis)

Blue grama grass (Bouteloua gracilis)

Three Arboretum All-Star Plants for Central Valley Wildlife Gardens

The horticulture staff at the UC Davis Arboretum has selected fifty Arboretum All-Star plants that are reliable, easy to grow, and will broaden the seasons of color, fragrance and beauty in Central Valley gardens (see Arboretum All-Stars: Great Plants for Central Valley Gardens, Pacific Horticulture, April 2007). The following are just a few of our favorite habitat plants for Central Valley gardens. Autumn sage (Salvia greggii), originating in the mountains of eastern Mexico, has been hybridized and selected to provide flowers in a variety of colors including red, pink, coral, and yellow. Our favorite is the cultivar ‘Scott’s Red’, an early and long bloomer with prolific flower production in spring and fall, and scattered flowering in between. Hummingbirds visit it frequently, as do pipevine swallowtail butterflies. It prefers full sun and needs irrigation only every two weeks in summer, but it will tolerate more frequent watering and part shade.

Toyon (Heteromeles arbutifolia), a medium to large, evergreen, native shrub, deserves more use in designed landscapes. It prefers well-drained soils and thrives with only twice-monthly irrigation in either full sun or afternoon shade. In spring, it produces open panicles of tiny white flowers that provide nectar and pollen for an array of beneficial insects. In winter, the large clusters of showy red fruits (see cover photograph) are a favorite of migrating birds, especially cedar waxwings, and add color to the winter garden.

Grasses are an important part of the wildlife garden as sources of pollen and places to rest and hide from predators. Blue grama grass (Bouteloua gracilis) is a small, native grass useful in smaller gardens for its vertical foliage and attractive toothbrush-like inflorescences. A warm-season grass, it is green in early summer but dries to spikes of gold in the low-water, full-sun garden. Plant it with winter-growing, summerdormant natives such as blue-flowered Triteleia laxa.

For Further Reading

Adler, Judy. An Ecologist’s Garden. Pacific Horticulture, Winter 1997, pp. 43-48.
Bauer, Nancy. The Habitat Garden Book. Sebastopol, CA: Coyote Ridge Press, 2001.
Bornstein, Carol. Primary Colors: Three for the Hummingbirds. Pacific Horticulture, July 2005, pp. 3-5.
Brigham, Steve & Donna. Our Plant Collection is for the Birds (and Butterflies, Too!). Pacific Horticulture, January 2007, pp. 32-37.
Brown, Margaret and Joanne Taylor. Hallberg Butterfly Gardens. Pacific Horticulture, October 2002, pp. 3-6.
Frey, Kate. The Milkweeds. Pacific Horticulture, July 2000, pp. 16-19.
———. The Pleasures of a Habitat Garden. Pacific Horticulture, July 2001, pp. 20-26.
Graves, Pria. Thanks to Our Feathered Friends. Pacific Horticulture, October 2006, pp. 26-28.
Greenberg, Katherine. A Garden Shared. Pacific Horticulture, Winter 1995, pp. 31-37.
Hartlage, Richard. A Garden Sanctuary for the Children of the Moon. Pacific Horticulture, Summer 1999, pp. 32-39.
Reinhard, Harriet V. Gardening for Butterflies. Pacific Horticulture, Winter 1987, pp. 48-54.
Schieffelin, Jack. A Wildlife Garden. Pacific Horticulture, Fall 1998, pp. 39-47.
Schindler, Mary, et al. Bees in the ‘Burbs. Pacific Horticulture, April 2003, pp. 29-35.
Thompson, Ken. Bugs in the Border, The Garden, May 2004, pp. 346-349.
Tweit, Susan. Creating Buzz, Audubon, May-June 2007, pp. 29-32.
Windom, Grant T. Bird Gardens in the Northwest. Pacific Horticulture, Winter 1983, pp. 6-8.

Recommended Websites

The Garden Habitat Network,
www.gardenhabitat.net

National Wildlife Federation, www.nwf.org

Butterflies and Moths of North America,
www.butterfliesandmoths.org

Art Shapiro’s Butterfly Site, butterfly.ucdavis.edu

If You Should Like to Visit . . .

The UC Davis Arboretum, on the Davis campus, stretches two miles along the banks of the old north fork of Putah Creek, with headquarters on LaRue Road. For more information about the Arboretum, the Arboretum All-Stars program, membership, volunteer opportunities, or directions and a map, please call 530/752-4880 or visit arboretum.ucdavis.edu.