For 90 years, the Santa Barbara Botanic Garden (SBBG) has been conserving California’s precious flora through its garden displays, research, and education programs. Since the inception of its plant introduction program in 1965, SBBG has introduced 41 cultivars. SBBG focuses on great plants from the California floristic province that can be used as substitutes for non-native offerings in the ornamental landscape trade. Native cultivars pose less of an invasive threat and help compensate for native plant habitat that is lost to development. The popularity and increasing use of native cultivars also help to preserve wildlife and pollinator relationships that are threatened by decreasing native plant populations.
Knowledge is essential to growing natives. The SBBG introduction program grows prospective plants in different locations on its grounds for two to three years to evaluate their tolerance for a variety of garden conditions. Promising plants are then shared with a network of partners throughout the state, which includes commercial nurseries and arboreta that grow the plants on for another two to three years. These partners share their observations and advice on the prospective introduction. Past SBBG introductions, such as Elymus condensatus (syn. Leymus condensatus) ‘Canyon Prince’ and Iris ‘Canyon Snow’, have set a high standard for garden performance and beauty.
Senecio palmeri ‘Silver and Gold’
‘Silver and Gold’ is a moderately woody sub-shrub that rarely reaches more than two feet tall and wide. Densely felted white leaves enable the plant to withstand high heat and make this a good choice for full-sun locations. The cultivar name references the plant’s lovely golden flowers. Hardy in dry conditions, ‘Silver and Gold’ also tolerates semi-shade and more generously watered gardens. A definite frost range has yet to be determined, though it is clear that plants can take a frost; plants have overwintered well in the Bay Area and in Davis, and survival to at least 25°F seems sure. During trials, ‘Silver and Gold’ grew easily in the SBBG garden and received a good response from our network of growers.
Early explorers erroneously called this plant Guadalupe Island white sage, but this senecio shows its membership in the Aster family as soon as its golden-centered, yellow, daisy-like blossoms open. Plants usually bloom in spring with occasional rebloom in midsummer. And, like most asters, the flowers offer nectar and pollen freely to many insects and other pollinators.
Senecio palmeri is native to Guadalupe Island, an isolated, large, rocky island 150 miles off the coast of Baja, California. The island is rarely visited by tourists or the public, so this plant is still rare in the trade. With diverse rock and soil types, the primary characteristics of this very arid habitat are low rainfall, well-drained soil, wind, and intense sunlight.
‘Silver and Gold’ is beautiful planted in swathes in the front to middle of the border, and it has many garden applications. It has done moderately well in loamy soil, though it prefers well-drained conditions. It requires more restricted watering if grown in clay soil. Both propagation and cultivation are easy. The only notable pests have been occasional rabbit browsing or periodic aphid infestations on new spring growth.
Grindelia stricta ssp. platyphylla ‘Ray’s Carpet’
Another new SBBG release is the ground-covering gumplant Grindelia stricta var. platyphylla ‘Ray’s Carpet’. Found by nurseryman Ray Walsh in the 1980s and shared with several botanic institutions, we’ve named this cultivar in remembrance of Walsh, an early pioneer in both native landscaping and restoration. As operator of Wildwood Nursery in Upland, California, Walsh’s most lasting introduction to the plant trade is Artemisia californica ‘Montara’, which he collected from Montara Mountain on the San Francisco Peninsula.
‘Ray’s Carpet’ stays under eight inches tall and spreads to two feet across. It is covered with two-inch, yellow, daisy-like flowers in midsummer. The plant is successful in low borders or massed as a groundcover in full to partial sun. An evergreen, ‘Ray’s Carpet’ is adaptable to many soil types. It is drought tough along the coast and only needs modest summer water inland, making it a good choice for difficult or hot spots in the garden. Remove faded flowers in the fall to keep the plant looking its best. This gumplant is equally as valuable as Walsh’s better-known selection, and is worthy of wider use.
Senecio palmeri ‘Silver and Gold’ is available through a licensing agreement with Santa Barbara Botanic Garden and from Suncrest Nurseries, Native Sons Nursery, and San Marcos Growers. No licensing agreement is necessary for Grindelia stricta ssp. platyphylla ‘Ray’s Carpet’. Mother stock for either plant can be ordered from the SBBG at www.sbbg.org.