By T. Eric Nightingale, UC Master Gardener of Napa County
It may surprise you but California has a good deal in common, environmentally speaking, with South Africa. Both have a variety of climate zones, many of which overlap. Many plants from South Africa will grow well in Napa Valley, especially with proper care.
You are doubtless already familiar with some South African plants. Red hot pokers (Kniphofia uvaria), with their spiked yellow and red blooms, are used frequently in Bay Area gardens. Two South African irises, Dietes bicolor and Dieties grandiflora, are present in what seems like two out of three shopping center parking lots. Even the popular bird of paradise, Strelitza reginae, is native to this region.
Many other less-common South African plants will also grow well in Napa. If you are curious about a new plant but unsure if it will grow well in your area, look into its native climate. While the Bay Area has many microclimates, we generally have a warm-summer Mediterranean climate.
This description comes from the Köppen climate-classification system used by many to identify climate zones around the world. You can find a color-coded map online showing areas with similar climates. If a plant comes from an area with the same color code as your garden, it should be a good choice for you. Compare the climate maps of California and South Africa and you will see many of the same colors.
We have native salvias here in California, but Africa also has some members of the genus. A personal favorite of mine is Salvia africana-lutea. It has a pleasant smell and small, dusty-green leaves. The flowers are rust-brown, giving rise to its common name: dune sage. That may not sound appealing, but the blooms and leaves create a color contrast that is attractive in the proper setting.
Another lovely plant in this genus is Salvia dolomitica, conveniently known as South African sage. Its silver-gray foliage makes a background to delicate purple flowers. The calyx—the leaf-like structure that holds the flower—starts out burgundy but turns pink with age. However, my favorite thing about Salvia dolomitica is its fragrance, an intoxicating blend of floral and herbal aromas befitting the plant's elegant appearance.
While some South African plants, such as Dietes, feel so at home here they need almost no help from us, others need a little extra care to remain healthy. Often, this means amending your garden soil to improve drainage or protecting the plant from frost. This is particularly true of plants in the Proteacea family. Leucospermum cordifolium is a shrub that grows large, colorful flowers with extended styles, often called “pincushions”.
A similar plant in the Protea family, the Leucodendron salignum,produces a flower that resembles a pine cone in shape, but in colors ranging from yellow to silver. These plants must have exceptional drainage or their roots will quickly rot. They are also sensitive to frost and can only take low-phosphorus fertilizer. Even though they require this special attention, they are drought tolerant once established. And oh, are the flowers worth the effort!
Many succulents are native to South Africa and will perform well in Napa Valley. Aloe brevifolia is a stubby-leaved, clumping plant that produces orange flowers in fall and winter. It is frost tolerant as well, which is not a common trait in a succulent. Delosperma cooperi, a personal favorite, is a vine-like plant that forms dense mats along the ground and over the edges of planters. It is very cold hardy and produces dozens of pink flowers. When the blooms appear in spring and fall, they will add thick swaths of color to your garden.
Some of the most striking South African plants are bulbs. Freesia, Crocosmia and Gladiolus are familiar, but there are many others. One of my personal favorites is Babiana rubrocyanea, whose flowers have vibrant purple petals with a bright red center. Equally as attractive is Sparaxis elegans, which produces a delicately-colored orange and maroon bloom.
These bulbs are interesting because they thrive in clay soil and are summer-deciduous. During the hot months they die back to the ground and require no water at all. In fact, more than a sprinkling of water in summer will likely cause them to rot. Come spring, however, their leaves return and the flowers burst forth in all their glory.
I encourage you to explore the many plants from South Africa. You just might find a perfect plant for your garden.
Next workshop: “Succulents Celebration!” on Saturday, July 20, from 9:30 a.m. to 11:30 a.m., at the University of California Cooperative Extension, 1710 Soscol Avenue, Napa. Learn why succulents have become the trendiest members of the plant kingdom. For more details & online registration go to http://napamg.ucanr.edu or call 707-253-4221
The UC Master Gardeners are volunteers who provide UC research-based information on home gardening and answer your questions. To find out more about upcoming programs or to ask a garden question, visit the Master Gardener website (http://napamg.ucanr.edu) or call (707) 253-4221 between 9 a.m. and noon on Mondays, Wednesdays or Fridays.