North America Native Plant

Blue Threeawn

Botanical name: Aristida purpurea var. nealleyi

USDA symbol: ARPUN

Life cycle: perennial

Habit: grass

Native status: Native to the lower 48 states  

Synonyms: Aristida glauca (Nees) Walp. (ARGL7)  âš˜  Aristida nealleyi (Vasey) Vasey (ARNE9)  âš˜  Aristida purpurea Nutt. var. glauca (Nees) A.H. Holmgren & N.H. Holmgren (ARPUG2)  âš˜  Aristida reverchonii Vasey (ARRE9)  âš˜  Aristida stricta Michx. var. nealleyi Vasey (ARSTN)   

Blue Threeawn: A Graceful Native Grass for Water-Wise Gardens If you’re looking to add some wispy, blue-green elegance to your drought-tolerant landscape, meet blue threeawn (Aristida purpurea var. nealleyi). This delicate native grass might not be the showiest plant in your garden, but it brings a subtle beauty and ecological ...

Blue Threeawn: A Graceful Native Grass for Water-Wise Gardens

If you’re looking to add some wispy, blue-green elegance to your drought-tolerant landscape, meet blue threeawn (Aristida purpurea var. nealleyi). This delicate native grass might not be the showiest plant in your garden, but it brings a subtle beauty and ecological value that makes it worth considering for the right setting.

What is Blue Threeawn?

Blue threeawn is a perennial grass native to the lower 48 states, with a particular fondness for the American Southwest and Great Plains. You might also encounter it under various scientific synonyms, including Aristida nealleyi or Aristida glauca, but they’re all referring to this same graceful grass.

This native beauty naturally occurs across a surprisingly wide range of states, from the desert landscapes of Arizona and Nevada to the prairies of Kansas and Texas, and even reaching as far as Illinois and Vermont. Its adaptability across such diverse climates speaks to its resilience and versatility.

Why Grow Blue Threeawn?

Blue threeawn shines in water-wise and native plant gardens. Here’s what makes it special:

  • Exceptional drought tolerance once established
  • Low-maintenance growth habit
  • Provides habitat and structure for wildlife
  • Adds fine texture and movement to landscape designs
  • Supports native ecosystem health

Garden Design and Landscape Use

This grass works beautifully in xeriscaping projects, native plant gardens, and naturalized areas. Its fine, blue-green foliage provides excellent textural contrast when planted alongside broader-leafed native perennials or shrubs. Blue threeawn is particularly well-suited for:

  • Desert and semi-arid landscape designs
  • Prairie restoration projects
  • Water-conserving residential gardens
  • Wildlife habitat gardens

Growing Conditions and Care

Blue threeawn is refreshingly easy to grow, especially if you can provide conditions similar to its native habitat. Here’s what it needs to thrive:

Sunlight: Full sun is essential for healthy growth and the best blue-green coloration.

Soil: Well-draining soil is crucial. This grass tolerates poor, sandy, or rocky soils better than rich, heavy clay.

Water: Once established, blue threeawn is highly drought tolerant. Water regularly during the first growing season, then reduce to occasional deep watering during extended dry periods.

Hardiness: Suitable for USDA zones 4-9, making it adaptable to a wide range of climates.

Planting and Maintenance Tips

Plant blue threeawn in spring after the last frost, or in fall at least 6-8 weeks before your first expected freeze. Space plants according to your design goals – closer for a dense groundcover effect, farther apart for individual accent clumps.

Maintenance is minimal once established. You may choose to cut back the grass in late winter or early spring before new growth emerges, though this isn’t strictly necessary. Be aware that blue threeawn may self-seed in favorable conditions, which can be either a benefit or something to manage depending on your garden goals.

Wildlife and Ecosystem Benefits

While blue threeawn is wind-pollinated rather than attracting specific pollinators, it provides valuable ecosystem services. The grass structure offers nesting sites and cover for small wildlife, and its seeds can provide food for birds and small mammals.

Is Blue Threeawn Right for Your Garden?

Blue threeawn is an excellent choice if you’re creating a water-wise garden, working on habitat restoration, or simply want to incorporate more native plants into your landscape. Its subtle beauty and ecological benefits make it particularly valuable for gardeners committed to sustainable, regionally appropriate plantings.

However, if you’re looking for a dramatic focal point or need a grass for high-traffic areas, you might want to consider other options. Blue threeawn’s charm lies in its quiet grace rather than bold statement-making.

For gardeners in its native range seeking an authentic, low-maintenance grass that supports local ecosystems, blue threeawn offers an opportunity to create beautiful, sustainable landscapes that celebrate the natural heritage of their region.

Blue Threeawn

Classification

Group

Monocot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Liliopsida - Monocotyledons

Subclass

Commelinidae

Order

Cyperales

Family

Poaceae Barnhart - Grass family

Genus

Aristida L. - threeawn

Species

Aristida purpurea Nutt. - purple threeawn

Plant data source: USDA, NRCS 2025. The PLANTS Database. https://plants.usda.gov,. 2/25/2025. National Plant Data Team, Greensboro, NC USA