May 19, 2018
Given the choice between ‘Blond Ambition’ and ‘Purple Stipa,’ which would you choose? These are not the names of rock bands, but rather California native grasses that make your garden rock. They sequester carbon, lower your water use, provide wildlife habitat and beautify garden spaces.
While the majority of grasses thrive in sun, there are grass-like plants called sedges and rushes that tolerate shade. This rhyme helps distinguish the plants:
Sedges have edges
Rushes are round
Grasses have nodes
From the top to the ground.
The hills of our coastal Marin landscape were once covered with bunchgrasses green in winter and spring, and golden in summer and fall with native wildflowers abounding. A look into the past can be seen on four acres at Old St. Hilary’s Historic Preserve in Tiburon. One grass growing there is our official state grass, ‘Purple Stipa’ or purple needlegrass, scientific name Nassella pulchra, meaning beautiful. It can be added successfully as an accent in gardens, but that cannot be said of some non-native grasses found in many nurseries. Threats posed by non-natives include seeding around where they are not welcome, crowding out native flora and changing soil conditions.
Two non-native grasses proving to be as invasive as pampas grass are Mexican feather grass, scientific name Nassella tenuissima, and Chilean needle grass, Nassella neesiana. These should never be planted in California. Gardeners are increasingly reluctant to plant Pennisetum setaceum, common name fountain grass, because of spreading habits. When in doubt, check with the California Native Plant Society and the UC Cooperative Extension Office in Novato before planting.
While many members of the grass, sedge and rush families provide abundant planting choices, don’t forget to study the light, soil, propagation method and water conditions when making a selection. Generally, sedges prefer moist conditions although some are drought-tolerant. In hot inland areas, they need some shade. Sedges self-sow and spread by runners with deep roots. Some native sedges grown in home gardens include Carex pansa and Carex praegracilis, both with dark green foliage that can form a thick carpet. A frequently planted non-native sedge is Carex divulsa, common name Berkeley sedge. Native to Europe, it tolerates full sun to shade and prefers regular water.
Rushes are members of the Juncaceae family. Evergreen perennials, their round stiff stems bear bronze flowers near the tips. Juncus patens, commonly called California grey rush or spreading rush, is an attractive selection for Marin gardens. It prefers regular water and sunny conditions but tolerates drought and shade. Rushes should be divided every few years as clumps die out. Like sedges, rushes will roam spreading by rhizome. The spread of rushes can be controlled by planting in containers.
Many of our California native grasses have beautiful flowering structures with some of the showiest belonging to California fescue, California melic, ‘Blond Ambition’ and ‘Purple Stipa.’ Grasses are characterized by their seasonal patterns; cool season grasses are green in winter and bloom in spring while warm season grasses are green in summer and bloom in the fall. California melic likes sunny coastal conditions, but in hot inland areas it needs shade. Cool season grasses like melic, bloom in spring and require little summer water.
California fescue flowers in spring and summer with robust clumps sometimes reaching 2 feet high. It performs best in light shade with low water in summer. ‘Blond Ambition,’ Bouteloua gracilis, is a warm-season perennial grass with clumps to 16 inches and shiny umber blooms that fade to straw color. Our California native ‘Purple Stipa’ has spring blooms reaching as high as 3 feet.
For more inspiration on using ornamental grasses as accents in the garden, visit the UC Davis Arboretum, especially the Mary Wallis Brown Garden of California Native Plants. Grass and grass-like plants will make your garden rock.