Our climate is characterized as Mediterranean, with hot, dry summers, cool, wet winters, and moderate frost. Yet our rainfall averages less than 8 inches a year, making Kern County a desert by most definitions.
Some regions of the world have similar conditions and more water, which makes their flora well-suited to irrigated Bakersfield gardens. Many choice ornamentals were discovered far south of the equator in South America, parts of Africa, and the land down under.
Following are some great cultivars introduced from Australia and New Zealand.
Eucalyptus trees are so widely planted in Southern California one might think they were native. They look especially good in groves, like those at the south end of the State Farm complex near the post office on Coffee Road. Three particularly good eucalyptus for our area are the fuchsia-flowered gum or red ironbark (E. sideroxylon) with a dark red-brown trunk and colorful flowers in summer, the peppermint-scented willow gum (E. nicholii) with small foliage, weeping branch tips, and a minty scent to the crushed leaves (very pleasant along a walkway or patio), and the silver dollar gum (E. cinerea) with shiny, waxy-coated foliage that makes a great contrast to its ridged, light brown bark. Not all eucalyp
tus shed their bark. These three are surprisingly tidy members of an otherwise rather messy genus.
One important consideration regarding eucalyptus is their root systems, which spread wide and can lift masonry. Trying to restrict the root zone with underground barriers can work, but is liable to make the tree unstable. This happened in my own yard due to our heavy clay soil; we had a 40-foot tree removed because it was loose at the roots, tipping in the wind. The root barrier I'd installed kept the roots from spreading wide enough to stabilize the tree.
Mirror plant (Coprosma) are evergreen broadleaved shrubs with very shiny leaf surfaces. The flowers are tiny and hide among the foliage. In the past few decades, several outstanding cultivars of mirror plant have appeared in local nurseries. Of greatest interest are those variegated and bronze-toned types that add 12-month color with little care. They look particularly good against a backdrop of dark green foliage or beside a flowering border.
Grevillea is a large genus including both trees and shrubs, all with characteristic curled buds in flower clusters. The silk oak (G. robusta) is a tall forest tree with divided fern-like foliage and abundant orange blooms in early summer. It is borderline-hardy in our region, doing better in areas with less frost. In Los Angeles County there are hundreds of them planted along freeway embankments, which seems to me a perfect place for them, as they take little care, tolerate heat and drought, and are exceptionally untidy, constantly shedding foliage and flower parts.
The shrubby grevilleas also are well-adapted to hot, dry conditions. They make excellent barrier plants with their stiff pointed leaves, and are unappetizing to varmints and deer. A hybrid called grevillea x noelii has shiny green foliage and reddish flowers that last throughout summer into fall. Wooly grevillea (G. lanigera) has gray-green foliage and is available in a range of cultivar sizes from 7-foot shrubs to groundcovers.
Kangaroo paw (Anigozanthos) is a durable perennial that tolerates planting near eucalyptus (which few flowers can abide). The foliage resembles that of Iris, but is deep green and rather stiff. The bloom consists of colorful bracts with a fuzzy coating (thus the common name) and green, tube-shaped flowers.
Many breeders have introduced kangaroo paw cultivars in a range of sizes and colors. All take full sun to part shade, and are not picky about soil type.
Geraldton waxflower (Chamelaucium) is worth trying in less frost-prone parts of town, wherever Jacarandas don't die back much in cold years. These are airy, open shrubs with bright flowers that take heat extremely well. A local beekeeper told me he has a large planting of Geraldton waxflower because few other plants produce much nectar in our hottest conditions. Flower colors range from white to pale pink to deep rosy pink, depending on cultivar.
Bottlebrush (Callistemon) includes shrubs and small trees with bright, red flower clusters of hair-like stamens that cover the twigs. The larger species are liable to suffer frost damage in many parts of town in cold years.
Surprisingly it's the smallest cultivar that takes our climate extremes the best, called Little John bottlebrush. This is a true dwarf, growing only a few feet high and wide. It takes pruning well, and has dark grey-green foliage that contrasts nicely with other garden colors.