We usually equate the word “grass” with “lawn,” but did you know there are many durable and decorative grasses that can be combined with other flowering perennial plants to create a lovely water-wise garden?
Although the term “ornamental grasses” can refer to both true grasses and other grass-like plants, we’ll focus on those in the grass family (Poaceae) here.
Ornamental grasses come in many forms and colors, and they can be used in different ways. The taller species are ideal when used as single accent plants in small gardens or large pots. In more expansive settings, grasses of all sizes are attractive when planted in rows, small clusters, or freeform drifts.
Grasses are essentially foliage plants. Their flowers tend to be inconspicuous and earthy-colored (cream, tan, gold, or brown), but the mature flowering spikes still add plenty of visual interest, especially since the long stalks look absolutely gorgeous when gently waving in the breeze!
Most ornamental grasses can be allowed to grow with minimal maintenance, but most perform best when pruned every year or two. Avoid shearing grass clumps into 1- to 2-foot-high balls (a common but improper and unattractive practice). Instead, they should be cut down to a few inches above ground level in late winter. Fresh new growth will emerge in spring to rejuvenate the clumps.
Ornamental grasses generally thrive in fun sun or light shade. Most prefer well-drained soils, but some tolerate clay soil. Here are some of the best selections for our Central Valley:
California Native Ornamental Grasses
Deer grass (Muhlenbergia rigens). A durable 4-foot grass with arching, narrow, green leaves and graceful tan flower spikes. Cut nearly to the ground every three years, and periodically rake out dead foliage.
Blue grama grass (Bouteloua gracilis). A green-leaved species that grows to 2 feet tall. Its dense creamy-white seed heads look like narrow flags or “eyelashes” held at nearly right angles to the stems; when ripe, they curl and often turn purplish. The cultivar ‘Blond Ambition’ is especially attractive.
Non-Native Ornamental Grasses
Feather reed grass (Calamagrostis x acutiflora). An upright grower up to 5 feet tall, with pinkish or plum-colored flower spikes that mature to dark tan or golden-brown. ‘Karl Foerster’ is an excellent cultivar.
Pink muhly grass (Muhlenbergia capillaris). This fine-leaved grass grows 4 to 5 feet tall and wide. It has showy blooms from late summer through fall, bearing dark pink flowers on delicate, plume-like spikes. The dwarf cultivar ‘Regal Mist’ has prolific pink blooms; “White Cloud’ has ivory flowers.
Blue oat grass (Helictotrichon sempervirens). With steely blue foliage and a spiky-looking habit, this attractive grass grows 1½ to 2 feet tall. Its thin flower spikes emerge bluish white and age to a golden hue.
Invasive Grasses: Do NOT Plant
Some ornamental grasses once commonly planted in landscapes are now known to be invasive. They multiply rapidly and escape into natural areas, where they cause significant ecological and economic damage by displacing native plant and animal species, increasing fire hazard, and interfering with grazing land and crop production. They are also extremely difficult and costly to eradicate once established.
Avoid planting these, and remove them when possible:
Pampas grass (Cortaderia selloana). Originally from South America, this grass has become a serious problem in California, especially in coastal areas such as Big Sur. Mature clumps can tower up to 10 feet tall or more; the stiff, dense leaves have sharp, saw-toothed edges; and the root systems are tough and very deep.
Mexican feather grass (Nassella/Stipa tenuissima). This is a beautiful and delicately-textured grass, but it self-seeds prolifically and spreads quickly. Unfortunately, it’s still grown and sold in the nursery trade.
Green fountain grass (Pennisetum setaceum). This grass blooms in summer, bearing purplish plumes that look like foxtails. (Note: Colorful, sterile, noninvasive varieties are being developed and are good alternatives. Examples: ‘Rubrum,’ with deep purple leaves, and ‘Fireworks,’ with burgundy- or magenta-striped leaves.)