If you are considering installing a drought tolerant garden on your property or including more drought tolerant plants in your landscape, one plant that should come standard is blue sage. Its silvery-green foliage, large, abundant, purple-blue flower stalks, and attractive mounded shape, make it an excellent feature in any water-efficient garden bed.
Salvia pachyphylla is in the mint family (Lamiaceae). It has several common names which it shares with several other plants: blue sage, Mojave sage, rose sage, mountain desert sage, giant-flower sage. For this post we will refer to it as blue sage; however, if you’re looking to purchase it, make sure to verify the botanical name. Blue sage is a subshrub that can grow up to 3 feet tall and 3 feet wide. It tends to remain smaller – around 1-2 feet tall – in its native habitat. It is found in the southwestern states of the United Sates on dry, rocky slopes and flats at elevations between 5,000 – 10,000 feet. The leaves are oppositely arranged and covered with fine hairs that lay tightly against the leaf surface giving the foliage its silvery appearance. Like all other sages, the leaves of blue sage are highly aromatic.
The flowers appear in compact clusters on spikes that extend upward from the branches. The inflorescences can be several inches long. They have numerous large, purple bracts that appear in a whorled pattern along the spike. The violet-blue flowers are small but prolific and appear between the bracts surrounding the stalk. Flowering occurs throughout the summer (July-September in its native range). The flowers attract droves of pollinators including bees, butterflies, and hummingbirds. Blue sage is especially beneficial to native pollinators. In fact, while taking photos for this post, I noted that the flowers were being visited by several bumblebees. Its benefit to pollinators is another great reason to include this plant in your landscape.
Blue sage is a very drought tolerant plant. Once it is established it requires only occasional watering throughout the summer in order to keep it looking good. It performs well in a variety of soil types, but like most drought tolerant plants it is best placed in well drained soil. Heavy soils can be amended by mixing in things like sand, lava rock fines, and compost at planting time. It prefers full sun and is winter hardy to USDA hardiness zone 5, especially if planted in an area where the soil is relatively dry throughout the winter. Blue sage is a long lived plant and can be kept in shape by cutting back the spent flowers in the fall. The folks at Plant Select recommend planting blue sage with, among other things, penstemon, coreopsis, and creeping veronica.
Photos were taken at Idaho Botanical Garden in Boise, Idaho.