Tom Karwin, On Gardening | ‘Super shrubs’ thrive in coastal region

Care for your garden

I have written about the genus Salvia over the years and mentioned it most recently in a column about seasonal pruning. I regard these plants as “super shrubs” because of the genus’ numerous species and hybrids, the range of plant characteristics and blossom colors, and the ease of cultivation in the Monterey Bay area.

Salvias comprise the largest genus within the Sage plant family (Lamiaceae), with close to 1,000 species plus uncounted hybrids. They are native to several part of the world: Central America and South America (approx. 600 species); Central Asia and the Mediterranean (250 species); and Eastern Asia (90 species).

The genus includes great variation. Visit Flowers by the Sea to explore its online Salvia database by blossom color, bloom season, preferred exposure, and other categories.

Today’s column came to mind because of seasonal maintenance tasks, beginning with pruning, which is best done for most Salvias before the beginning of spring. The target date is March 20 so there’s ample lead time for the pruning schedule.

Sunset’s Western Garden Book recommends pruning Salvias in late winter or early spring, when “vigorous new growth is emerging from the plant base.” Then, tip-pinch plants during the growing season or cut them back by one-third to control size and shape.

This is good, basic pruning guidance for this genus, but the Salvia genus includes a wide variety of plants, so pruning practices vary within the genus. The Flowers by the Sea website recommends pruning Salvias according to four broad categories of the plants.

Rosette Types, which develop low mounds of foliage from which flower spikes emerge. Hummingbird Sage (Salvia spathacea) is a familiar example. Most plants in this category are winter bloomers, entering dormancy in summer. Summer-flowering varieties will go dormant in autumn. When dormant, cut flowering stems to the ground.

Evergreen, Woody Salvias, with the characteristics of a shrub, and could grow quite high. An example of this category is Karwinski’s Sage (S. karwinski), which can reach 10 feet tall. These plants can be pruned at any time of the year. Removing old growth encourages new growth and supports shaping of the plant’s size and shape.

Deciduous, Woody Salvias lose their leaves in the winter, but in the Monterey Bay area’s moderate climate do not die to the ground. A popular variety in this category is Autumn Sage (S. greggii), which blooms from spring to fall. After the last bloom, cut stems to the ground.

Deciduous or Semi-Evergreen, Soft-Stem Salvias lose all or most off their leaves at the end of the growing season and can be unsightly for those who prefer a neat garden. Mexican Bush Sage (S. leucantha), with purple and white blossoms, is a widely grown example in this category. These plants can/should be cut to the ground after the growing season. This might seem drastic, but they will come back quickly in the spring.

Here are examples of Salvias in my garden, selected to feature blossom color differences.

Friendship Sage (Salvia ‘Amistad’). This plant has large, purple-violet blossoms, and grows up to 5 feet high and 6 feet wide.

Red Velvet Sage (Salvia confertiflora). This native of Central and South America produces spikes of small, velvety, orange-red blossoms from late summer to mid-autumn.

Pineapple Sage (Salvia elegans ‘Elk Sonoran Red’). Known for the pineapple aroma and flavor of its foliage when crushed, this plant can spread easily in the garden, and may require periodic management. It grows to 4-ft. tall and 3-ft. wide in one season.

Forsythia Sage (Salvia madrensis). This example of a yellow-flowered Salvia has a blossom color like that of the Forsythia, an Asian shrub. S. madrensis grows vigorously to 10 feet tall and 5 feet wide, and blooms in the fall.

Hummingbird Sage (Salvia spathacea). This California native is a semi-evergreen herbaceous perennial that is just 1-to-2-feet tall, spreading to about 4 feet wide, with deep rose-pink flowers.

Pink & White Wagner’s Sage (Salvia wagneriana). This Central American species grows to about 6-ft; tall and wide, and, from November to March, produces a charming display of white bracts surrounding hot pink flowers.

My garden includes a large, raised bed with mixed varieties of Salvias. These plants have been growing well, and over time have spread to generate a dense grouping of plants. Collectivley, they discourage weeks quite well, but appear crowded. With garden help, we have cut most of these plants quite low and are now selectively lifting plants to share. They are now hard to identify and not looking their best, but they are healthy and well-prepared for spring growth. We’ll see if they are appealing to gardeners at the Santa Cruz Garden Exchange.

Enrich your gardening days

Explore the wide range of salvias for addition to your garden. The message of today’s column is that this genus offers such diverse varieties that one can be found to suit almost any garden planning interest. A very good time to acquire and install new Salvia plant is right now.

Advance your knowledge

Sources of information on cultivating Salvias include the following:

Flowers by the Sea (www.fbts.com/). This is a highly developed website with extensive information about species and hybrids of the Salvia genus, including photos, which are useful for plant identification. This is a valuable resource for navigating through the “salvia universe.” Flowers by the Sea also offers Salvia plants for purchase.

Salvia Entry, Wikipedia (en.wikipedia.org/wiki/Salvia). This site includes reliable basic information about the genus, and a list of links to more detailed information on twenty-six well-known species.
Sunset’s Western Garden Book, Kathleen Breznel, Editor (Sunset, 2001). This popular reference books includes five+ pages of summary information on selected Salvia species.

The New Book of Salvias: Sages for Every Garden, Betsy Clebsch, Author (Timber Press 2013). This gardener has been called “The Sage of Salvias” (pun intended) because of her enthusiasm for this genus and her practical advice on their cultivation, drawing upon her growing experience in the Monterey Bay area. Her book is a “must-read” for dedicated Salvia gardeners.

Gardener’s Guide to Growing Salvias, by John Sutton (Timber Press, 2004). This book is a useful complement to the Clebsch book, with a somewhat different perspective.

American Horticultural Society’s A-Z Encyclopedia of Garden Plants, Christopher Brickell & Judith Zuk, Editors (DK Publishing, 1996). Another valuable reference book, it includes authoritative brief descriptions of a long list of Salvia species.

The Cactus & Succulent Society of America will present the webinar, “Connections Between Cactus and Succulent Conservation, Research, and Cultivation,” at 10 a.m. Saturday. Presenter Peter Breslin, Ph.D.,” will explore multiple connections between contemporary and emerging research methods in plant conservation and the ways we raise our plants. Understanding climate variables, microclimate effects, geography, geology, soil, and some of the basics of plant physiology can increase growing success, even with challenging plants.”

Breslin is one of the authors of A Field Guide to Cacti and Succulents of Arizona, published by the Tucson Cactus and Succulent Society, soon in its third edition. He has been traveling to Baja California to find and photograph populations of rare cacti and succulents for the past 25 years. He recently moved to Los Angeles, CA, to teach biology and environmental science at Geffen Academy at UCLA, where he also hopes to continue several research projects.

To register for this free event, visit cactusandsucculentsociety.org/.

Tom Karwin is past president of Friends of the UC Santa Cruz Arboretum, Monterey Bay Area Cactus & Succulent Society, and Monterey Bay Iris Society, and a Lifetime UC Master Gardener (Certified 1999–2009). He is now a board member and garden coach for the Santa Cruz Hostel Society. To view daily photos from his garden, https://www.facebook.com/ongardeningcom-566511763375123/. For garden coaching info and an archive of previous On Gardening columns, visit http://ongardening.com. Contact him with comments or questions at tom@karwin.com.