When xeriscaping, you can add plenty of interest with varied textures and heights by including a few ornamental grasses in your landscape. We’re always tempted to think first about flower color, but less about interesting foliage. Placing a few ornamental grasses in a xeric landscape or container can add nearly as much impact as a pop of purple with less watering and maintenance.
Choose an ornamental grass that is native to your area, or a similar climate or condition, in place of a shrub or perennial flower. One of my favorite features of grasses is that they can grow tall and move in the wind. In containers, they often add height or contrast to draping and flowering annuals. Warm-season grasses seed out and provide winter interest, even if the foliage browns. They need shearing once a year in spring, a little water to jumpstart growth, and they’re off. If you choose one that’s not native to your area, such as the big-box store selection I found for my containers, make sure it can at least survive with less water or other conditions that differ. You might not get flowers or as much growth, but the grass will survive at least for the summer.
Another benefit of ornamental grasses is that they can serve practical purposes in a garden. Use them for erosion control by placing a small grouping at the bottom of a slope or terrace – and go for a medium-water selection such as Feather reed grass “Karl Foerster” (Calamagrostis arundinacea) here, since the rain or irrigation run-off from above supplies the extra water the plant requires.
Other great locations for grasses are along steps, pathways or corners, in front of dark walls or fences, and anywhere they will catch sunlight and breezes.
Sedges, rushes and some hardy bamboos also fall into the ornamental grass category when landscaping. Just be sure to check the zone, native location of the plant, and especially the sun and water requirements before planting the grass. Some actually do better in marshes – not a good choice for xeriscaping!
Grasses are among the easiest xeric plants you can have in your garden. They’re mostly free of pests and diseases. And although I love ornamental grasses, I have seen some gardens with only grasses and gravel. I think you need one or two other xeric plants to break up the look, but I’m not a professional landscaper. To my eye, just gravel and grass in a garden screams “dry!” It’ so easy to complement a low-water grass with a salvia, penstemon or gayfeather.
Some cool-season grasses bolt in the heat, but trimming off their seedheads can rejuvenate the plant, much like clipping off flowers of herbs to force growth back into leaves. Most ornamental grasses are warm-season selections, best planted in the spring. They need a little more water, up to once a week for xeric choices, for the first month or two. After that, water deeply only every few weeks or once a month in the hottest summer weeks. Some will spread, and it’s best to try to divide or dig up unwanted volunteers before they clump too tightly. Other than that, just cut back as directed. Allowing several grasses to overseed in winter could add to your fire hazard, so keep that in mind if you have them near your home or a commercial building.
A few xeric grasses
Silky threadgrass (Stipa tennuifolia). This hardy grass grows in all types of soil, uses little water, and loves full sun. That’s a bonus, since the silky seedheads reflect sunlight as they sway in the breeze. One caution for silky threadgrass is its high potential to reseed. That’s a plus in an untamed garden, but not in a more formal xeric landscape.
Big bluestem (Andropogon gerardii). This is one of our personal favorites. It can reach heights of four to five feet in summer, when it also rewards you with purplish flower spikes that emerge between the beautiful greenish-blue leaves. Some selections require more water than others, so check with the nursery or on the tag for details. Some are highly drought tolerant and thrive down to zone 4.
Dwarf fountain grass (Pennisteum alopecuroides). Purple fountain grass (P. setaceum) is a particular favorite of these dwarf varieties, but only makes it as an annual in our zones (5 through 7). Others fare better, although an unusually cold winter could kill them. Most have bright green foliage with bottlebrush flowers. Examples are “Hamelin,” a compact, mounding variety with ivory and gold flowers and “Moudry,” which has brownish-black flowers. One caution: You might have to protect dwarf fountain grasses from rabbits if they visit your xeric garden.