By Nancy Hawkins, UCCE Master Gardener
Three years ago, a garage remodeling project led to a landscaping opportunity; the establishment of a water-wise “cottage-style” garden in our front yard. Large shrubs (nandina, pineapple guava, Loropetalum chinense ‘Razzleberri’) and trees (crape myrtle, chaste, desert willow) provided the backbone of the yard. Among these trees and shrubs, I interspersed colorful aromatic, and butterfly and bee attracting salvias, or sages.
Salvias are a large group of garden plants that includes include annuals, perennials, and evergreen or deciduous shrubs. The genus Salvia (in the Lamiaceae, or mint family) offers Central Valley gardeners one of the largest and most versatile groups of plants available for water-wise gardening. The name salvia is derived from the Latin word salver “to heal” and salvias have been used for herbal and medicinal qualities since ancient times. Since the 1970s, the genus has produced some of the most popular garden ornamentals. Flowering salvias produce spikes of small, densely packed flowers atop aromatic foliage. These heat – and drought-tolerant beauties bloom from early to late summer in shades of blue, violet, red, pink, and white. Plants grow 18 inches to 5 feet tall, depending on the variety.
So, you may ask, what is my problem? My salvias are well-established three-year-old plants, and they bloomed in full splendor this past spring. Bees and butterflies were abundant. But, in the hot summer months, these same plants started looking leggy with spent blooms on the end of stems. Do I prune? If so, when? How much? How about irrigation? These are drought tolerant plants. Does that mean they need no water, little water, more water as they get bigger? Time for some research. Here is what I found.
Deadheading (removing faded blooms) is the most basic pruning practice that improves the health and appearance of any salvia, and can be done as needed. But, pruning for healthy plant growth and good bloom requires knowledge of the main types of salvias.
Rosette types, such as hummingbird sage (S. spathacea), give rise to erect flower stems surrounded by low mounds of foliage at the base of the stems. During bloom time, completely remove any flowering stems after they become spent. They may flower again. In our area, in the late fall, when growth stops, cut any remaining flower stems close to the ground. This pruning will strengthen roots for the next growing season.
Soft-stemmed deciduous sages have no woody growth. They may be a hardy type, returning year after year, or a tender perennial that needs to be replanted every year. Mexican bush sage (S. leucantha) is an example of this type. During the growing season, unsightly stems that have finished blooming can be cut to the ground. When the plant’s appearance becomes messy, it is okay to give these sages a “haircut”, trimming to 6-12 inches above the ground, which should stimulate new growth and flowering. In the late fall, completely prune off the spent stems close to the ground (3-4 inches). This severe pruning avoids a tangled mess next spring and controls pests over the winter.
Pruning for the larger, woody salvias is like the smaller ones. Autumn sages (S. gregii) species and the popular Cleveland sage (S. Clevelandii) are examples of woody stemmed salvias. In our area, they may become shrub-like. During the growing season, removing spent blooms stimulates new growth and flowering. For a tidy fall clean up after the last bloom and first frost, cut the spent stems to 56 inches above ground to prepare for the next growing season. Some of these salvias can grow to be up to 120 inches tall and 48 inches wide. Pruning these shrubby salvias involves removing old wood and crossed branches and can occur at any time. They can also be pruned to control height, width and attractive appearance and to encourage new growth.
Sharp well-honed needle nose pruners should be used on fine stems, and heavier duty anvil-blade or bypass models can be used for thicker stems.
Salvias, like any drought tolerant plant, needs a long drink of water applied to the ground (no sprinkling, please) at the edge of its canopy or drip line. In the perennial salvia garden, it is best to water infrequently, slowly and deeply. This process strengthens plant roots by making them travel outward and downward for water. The roots of well-established perennials may be down to 24 to 36 inches depending on the length of their roots at maturity. Most salvias are drought tolerant, once established, and do not need excessive summer irrigation. Salvia species vary in their water requirements, and some native CA species (Cleveland sage, for example) prefer very little irrigation.
The following information on determining soil moisture applies to any irrigation system. An easy method to determine soil moisture is to push a long-handled screwdriver, soil probe, or stiff piece of wire into the soil as far as possible. This serves as an indicator of how deeply water has penetrated the soil. When the implement cannot be pushed any further, it has reached dry soil. Most roots will not grow below that depth if the soil remains dry very long. Repeated probings after an irrigation will become more difficult over a period of days as the roots use soil water. It is time to re-irrigate if the probe can be pushed in about half the depth of the root systems in the area.
I hope this information is useful in caring for established plants in a drought tolerant garden. Salvias are forgiving, easy-maintenance plants and can be mainstays in your water-wise Central Valley garden.
The UCCE Master Gardeners will be available to answer your gardening questions in Visalia at the Farmer’s Market, 8 to 11 a.m., every Saturday in the Sears parking lot at Sequoia Mall.