Scientific: Muhlenbergia rigida (synonym: Muhlenbergia metcalfei)
Common: purple muhly
Family: Poaceae
Origin: Dispersed widely in rocky gravelly soils in the Southwestern United States and northern Mexico south to Chiapas, Mexico between 2,500 and 7,000 feet, and also at higher elevations in Ecuador, Peru, Bolivia, and Argentina.

Pronounciation: Muh-len-BER-gee-a ri-GI-da

Hardiness zones
Sunset
7-24
USDA 6-11

Landscape Use: Best planted in groups as an accent for bank covers, rock gardens, transitional landscapes. Best used when viewed from a distance.

Form & Character: Densely tufted, but airy, has a psychological cooling, and a softening effect in the landscape.

Growth Habit: Perennial bunch grass clumping to 2 to 5 feet in height with equal spread.

Foliage/Texture: Dense tufts of narrow, linear dull gray-green leaves from 1.5 to 6 feet long (1/8 inch wide); fine texture.

Flowers & Fruits: Purple florets borne loosely on extended panicles to 3 feet, flowers fade to beige brown for fruit set. Seeds extremely small, ie. 2.5 million per pound.

Seasonal Color: Flowering during late summer and autumn.

Temperature: Tolerant

Light: Full sun

Soil: Well drained

Watering: Weekly to bi-weekly deep irrigations in summer will keep plants robust.

Pruning: Shear (only once per year in late winter) or burn to the ground in late winter or early spring to remove the copius production of thatch (dead and slow to decompose leaves because of the dry climate) and re-induce vigor. Be careful, fire can be very dangerous! Make sure to check local laws and regulations before burning outdoors.

Propagation: Division anytime, seed in fall and early winter

Disease and pests: None in central Arizona, though air-borne fungi infect foliage in moister climates.

Additional comments: Purple muhly is a medium-sized bunch grass plant. Purple muhly, like its close cousin deer grass (M. rigens), is larger, more vigorous and less refined than M. capillaris. Thus, its ultimate larger size in Phoenix landscapes surprises most and can lead to the obligatory 'cue ball haircut' several times a year by horticultural clods.