Click here to watch a video on why to never plant Mexican needle grass
Why You Shouldn’t Plant Mexican Needlegrass in Your Garden
When planning a garden, it’s tempting to reach for plants that are drought-tolerant, low-maintenance, and visually striking. Mexican needlegrass (also known as Nassella tenuissima, formerly Stipa tenuissima) checks many of these boxes. Its fine, flowing green blades and soft, feathery seed heads add movement and texture to landscapes, especially in arid and Mediterranean climates.
But here’s the thing: this ornamental grass is an ecological nightmare in disguise.
1. It’s Highly Invasive
Mexican needlegrass is a prolific self-seeder. Its seeds are lightweight and equipped with long, twisted awns that help them latch onto animals, shoes, and even tires—spreading far beyond where it’s planted. Once it escapes gardens, it aggressively colonizes grasslands, open woodlands, and roadsides.
In fact, it has already become invasive in parts of Australia, California, South Africa, and other regions. It outcompetes native grasses and can rapidly dominate natural habitats, degrading biodiversity and altering fire regimes.
2. It’s Difficult to Control Once Established
Once needlegrass takes hold, removing it is a challenge. The seeds remain viable in the soil for years, and its fine, fibrous root system makes physical removal labor-intensive. Herbicide use is often ineffective against mature clumps, and repeated treatments may be required. Restoration of invaded sites can take years and significant financial resources.
3. It Threatens Agriculture
Mexican needlegrass poses a serious threat to grazing lands. Unlike native grasses, it becomes unpalatable and even harmful to livestock once it seeds. The sharp awns can injure the mouths, eyes, and digestive tracts of animals, particularly sheep and cattle. Pastures infested with this grass quickly lose their productivity, affecting both biodiversity and agricultural livelihoods.
4. Better Alternatives Exist
If you’re drawn to Mexican needlegrass for its ornamental qualities, there are safer, non-invasive alternatives that offer similar aesthetics without the ecological risks. Consider native or well-behaved grasses such as:
-
Muhlenbergia capillaris (Pink Muhly Grass)
-
Sporobolus airoides (Alkali Sacaton)
-
Bouteloua gracilis (Blue Grama)
-
Deschampsia cespitosa (Tufted Hairgrass)
- Aristida purpurea (Purple Three Awn Grass)
These species provide texture, movement, and resilience in the landscape—without becoming environmental hazards.
5. It May Be Regulated Where You Live
Due to its invasive potential, Nassella tenuissima is banned or restricted in several regions. Before planting anything, especially ornamental grasses, it’s important to check your local noxious weed lists or consult native plant societies. Ignorance isn’t a defense when it comes to invasive species.
Final Thoughts
What starts as a lovely addition to your garden can quickly spiral into an ecological problem. Mexican needlegrass is a textbook example of how “pretty” doesn’t always mean “harmless.” If you’re committed to a beautiful, sustainable garden, skip this grass and choose species that support, rather than harm, your local environment.
Your future self—and your ecosystem—will thank you. If you would like additional help with your landscape design project please don’t hesitate to call Cleator Landscape Design at 619 917 3644