Silky Thread Grass

Silky Thread Grass (Nassella [syn. Stipa] tenuissima)

 by Stephanie Burns

 In The Plant Finder’s Guide to Ornamental Grasses, Roger Grounds describes silky thread grass—also know as Mexican feather grass—as “an indispensable grass that contributes grace and elegance to the garden from spring until the depths of winter.” A fine-textured grass that’s characterized by striking color changes, it is mostly green from late spring to late summer, turning to pale buff in fall and winter. Delicate, slender leaves and airy flower heads catch the slightest breeze and play with the light, especially when backlit. The plant forms a dense fountain of cascading green or golden threads with feathery awns. Native to sage scrub and piñon-juniper woodlands, this cool-season grass reseeds readily, making it a good choice for naturalizing in meadows or on slopes, but be forewarned: in the garden it may spread into gravel mulches and patios.

 Planting and care: Plant in well-drained soil. Potted transplants establish more quickly when soil temperatures are warm. Take care not to bury crowns too deeply. Fertilizer is unnecessary. Cut established grasses close to the ground in spring to rejuvenate, and eliminate any that have more gray than gold leaves. Large plants may be divided in spring or summer. When seed heads begin to tangle and clump, comb or rake them off once or twice during the growing season to maintain a more groomed appearance and to control volunteer seedlings. Silky thread grass is disease- and pest-resistant.

 Landscape use: Striking planted alone or in large masses or drifts. Grown among other drought-tolerant and heat-resistant perennials, silky thread grass contributes interesting texture and color combinations. Provides excellent erosion control on slopes. Also good in containers.

 Propagation: In late spring, sow seeds on tilled soil by rolling or pressing the seeds into the soil rather than raking. Expect germination when soil has warmed to 70 degrees.

 Plant type: ornamental grass

Bloom time: early to late summer

Size: 18 inches high x 12 inches wide

Sun: full sun, part shade

Water: low once established

Soil: well-drained

USDA zones: 5–10

References:

 Grounds, Roger. The Plantfinder’s Guide to Ornamental Grasses (Timber, 2003)

Miller, George Oxford. Landscaping with Native Plants of the Southwest (Voyageur, 2007)

Native Plant Society of New Mexico, Central New Mexico Gardens: A Native Plant Selection Guide, rev. ed. (NPSNM, 2017)

Phillips, Judith. New Mexico Gardener’s Guide, rev. ed. (Cool Springs, 2005)