Five Little-Used Xeriscape Shrubs

Fortunately, there are many choices of drought-tolerant shrubs. And not only can they tolerate drier conditions, the fact that they are taller than most perennials and groundcovers helps them to compete better with weeds, giving them a greater survival potential in untamed, harsh or more industrial locations. In native ecosystems, it is often the shrubs that begin to pioneer a barren ground, and the shade and wind-protection they create, gives more favorable microclimates for other plants to germinate and find a home. There are many fine non-native shrubs for xeriscapes, but in this article, I am mostly going to describe some of my favorite native shrubs for drier conditions.

         It is remarkable that Curlleaf Mt. Mahogany, Cercocarpus ledifolius, is not better known. It is a broadleaf evergreen that grows to 10’-15’, sometimes 20’. The leaves are dark green above, paler beneath, and are adapted to droughty conditions, being narrow, leathery and having a slight curl. The light gray branches are very attractive and the form is upright and is generally improved with light shearing or deer-browsing. It seems to take three to four years of developing a strong root system before it begins to grow rapidly. Watering to get it established can be helpful, but it requires no supplemental water once it is well rooted. The flowers are not showy except to the bees, and the silvery spiraling seed heads can be ornamental. Curlleaf Mt. Mahogany makes a very beautiful evergreen specimen or screen.

         Mahonia fremontii is a desert “holly” with evergreen leaves that are blue, with reddish new growth in spring. Even though it can take a lot of heat and drought, I suspect it would make a more attractive landscape plant when given protection from the late afternoon sun and especially from the winter sun. In full exposure, the leaves dry out more, are less blue and drop more leaves in the fall. These fallen leaves, by the way, are very sharp and painful if you are trying to weed near this shrub, so I recommend not planting it with perennials but with other mulched shrubs in a border. (Mine is in the middle of my rock garden, and I use a shop vac to remove the dead leaves in the fall.) The spring flowers are yellow with a sweet and strong fragrance. The red fruits that follow are at first flat with little flavor, but later they thicken up and taste like delicious sour cherries. Mahonia fremontii will grow to 6’-8’ high and 4’-6’ wide.

         Paxistima canbyi is a Plant Select shrub for 2003. It is another broadleaf evergreen growing only 8”-12” high and 15”-20” wide. The flowers are inconspicuous, but the foliage is very beautiful, especially in winter. Mine has performed very well for years in part-shade, with very little supplemental water, but has stayed small. This species is not a native of the west; the Colorado native is Paxistima mysinites which is 10”-20” high.

         Rosa woodsii, Wood’s Rose is a native with many seasons of interest. I wouldn’t put it in full sun with no water, but I would definitely call it drought-tolerant. For a good performance, give it a little (or moderate) water with protection from late afternoon sun. It doesn’t require good soil, but a little compost could be helpful. It is a very suckering plant, so it is excellent for stabilizing banks and washes, but it is unsuitable for most perennial borders or rose gardens. It will succeed at 4” high or up to 4’ high and will form patches. The single, 5-petalled pink flowers can be pale, deep or even somewhat striped. Following the flowers are copious fruits (hips) which turn red, and the red fall color is glorious. I saw this one planted at the Unity Church in the 5’ space between the building and the sidewalk where it was contained and very beautiful.

         A star performer in the heat and drought of 2002 was the native cholla, Opuntia imbricata, also known as Candelabra Cactus. At the end of June when many other plants were in decline, this serious survivor was pumping out its showy red-purple flowers. It gets 4’-5’ high and 5’-7’ wide in many years. It does not like wet clay, but enjoys gravelly unamended soils. It can be contained with loppers and if unwatered in fast-draining soils, has little problem with weeds.