11 Invasive Ornamental Grasses to Avoid Planting in Your Garden
Avoid ornamental grasses that overtake borders and starve native plants of vital space.
Ornamental grasses are often praised for their resilience, architectural beauty, and low-maintenance appeal. But while these grasses can bring texture and movement to your garden, some species pose a serious threat to local ecosystems when grown outside their native range. Invasive ornamental grasses can outcompete native plants, damage habitats, and create long-term maintenance headaches for gardeners and land managers alike.
Contents
- What Makes an Ornamental Grass Invasive?
- Why Avoid Invasive Grasses?
- 11 Invasive Ornamental Grasses You Should Not Plant
- Managing and Removing Invasive Grasses
- Safer Alternatives to Invasive Ornamental Grasses
- Frequently Asked Questions
What Makes an Ornamental Grass Invasive?
A grass is considered invasive when it spreads outside cultivated areas, growing aggressively and outcompeting native flora. Often, these plants:
- Spread through rhizomes (underground stems), allowing them to regenerate even if the upper plant is removed.
- Produce copious seeds that disperse easily via wind, water, animals, or human activity.
- Lack natural pests, diseases, or herbivores in non-native environments, allowing unchecked spread.
Once established, invasive grasses can dominate disturbed soils, roadsides, and wild spaces, crowding out native species, altering fire cycles, and creating costly problems for gardeners and land managers.
Why Avoid Invasive Grasses?
- Biodiversity Threat: Invasive grasses displace native plants, reduce food and habitat for wildlife, and disrupt natural ecosystems.
- Maintenance Headache: They spread rapidly, often returning even after aggressive removal, requiring extensive labor to control.
- Legal Issues: Many states and municipalities restrict or ban certain invasive species.
- Misleading Beauty: The very traits that appeal to gardenersâhardiness, drought tolerance, vigorous growthâare what make these species risky invaders outside their home regions.
Remember: Whatâs invasive in one region may not be in another, so always check local regulations and lists of invasive plants for your area.
11 Invasive Ornamental Grasses You Should Not Plant
Many popular ornamental grasses turn invasive when grown outside their native environment. Here are 11 of the most problematic species:
- Miscanthus sinensis (Chinese Silver Grass)
- Fast-growing, with striking plumes and arching foliage.
- Spreads by wind-dispersed seeds and rhizomes.
- Known to invade roadsides, disturbed woodlands, and prairies.
- Phragmites australis (Common Reed)
- A giant grass found in wetlands and ditches.
- Forms dense thickets, outcompeting native wetland species.
- Can alter hydrology and reduce animal habitat diversity.
- Phalaris arundinacea (Reed Canary Grass)
- Aggressively spreads in wet areas and along waterways.
- Displaces native marsh and prairie grasses.
- Forms monocultures that degrade habitat value.
- Arundo donax (Giant Reed)
- A towering grass, sometimes mistaken for bamboo.
- Spreads via rhizomes; tough to eradicate once established.
- High water use and fire risk in dry climates.
- Nassella tenuissima (Mexican Feather Grass)
- Delicate, fine-textured plumes; attractive in gardens.
- Escapes cultivation via prolific seed production.
- Forms dense stands that outcompete natives, now invasive in several states.
- Spartina alterniflora (Smooth Cordgrass)
- Used historically for erosion control along coasts and wetlands.
- Colonizes mudflats and marshes, altering tidal habitats.
- Competes with native marsh plants and alters salt marsh ecology.
- Imperata cylindrica (Cogongrass)
- Listed as a federal noxious weed in the US.
- Extremely invasive, forming dense mats that choke out all other plant life.
- Can spread by both rhizomes and seeds; controls are difficult and often require repeated treatment.
- Pennisetum setaceum (Green Fountain Grass)
- Showy plumes and arching leaves; spreads aggressively in warm climates.
- Prolific seed producer; invades disturbed sites and wildlands.
- Note: Sterile cultivars such as Pennisetum setaceum âRubrumâ (Purple Fountain Grass) are generally considered less invasive.
- Microstegium vimineum (Japanese Stiltgrass)
- Small, wiry grass that grows in forests and lawns.
- Spreads rapidly, smothering young native plants and wildflowers.
- Often introduced by contaminated soil or mulch.
- Sorghum halepense (Johnsongrass)
- Once introduced as forage, now a troublesome weed in agricultural and natural areas.
- Spreads by both seeds and rhizomes; difficult to remove.
- Classified as noxious or invasive in many parts of the US.
- Leymus arenarius (European Beachgrass)
- Used for coastal erosion control, but invades dunes, crowding out native plants.
- Changes dune shape and ecosystem dynamics.
While some varieties or cultivars are bred to be sterile or seedlessâand are sometimes marketed as non-invasiveâmany of the above species (especially the “straight” botanical species) pose significant risks in most US regions.
Managing and Removing Invasive Grasses
If youâve already planted one of these grasses, or inherited them with your property, consider these strategies for control and removal:
What others are reading
- Manual Removal: Excavate root systems thoroughly; rhizomes left behind can regrow.
- Regular Mowing: Cut back repeatedly to exhaust reserves in roots and prevent seed set.
- Herbicides: Use selectively and only where safe; be cautious near water.
- Mulching and Solarizing: Smother regrowth after manual removal with deep mulch or solarization (covering the soil with black plastic to heat and kill roots and shoots).
- Dispose of plant material responsibly: Never compost invasive grass cuttings, seeds, or root fragmentsâbag and discard with trash.
Consistent maintenance is required to keep invasives in check. Full eradication may take several seasons, especially for deeply rooted or rhizomatous grasses.
Safer Alternatives to Invasive Ornamental Grasses
If you love the movement, color, and texture of ornamental grasses but want to avoid ecological pitfalls, choose native or non-invasive varieties. Consider these alternatives:
- Pennisetum alopecuroides (Fountain Grass): Many cultivars are sterile or non-invasive; check with local extension services for safe varieties.
- Schizachyrium scoparium (Little Bluestem): Native to North America; blue-green foliage, reddish fall color, and upright form.
- Sporobolus heterolepis (Prairie Dropseed): Fragrant, fine-textured, tufted grass ideal for borders and meadows.
- Panicum virgatum (Switchgrass): Attractive upright native, tolerant of a wide range of soils and climates.
- Cultivated Varieties Labeled as Sterile or Low-Fertility: Some newer ornamental grasses are specifically bred to be non-invasive by producing little or no viable seed.
Key Factors When Choosing Ornamental Grasses
- Always check if a species is invasive in your local region before planting.
- Prefer native speciesâthey’re adapted to local conditions and support native wildlife.
- Seek out certified sterile hybrids if you desire an ornamental plant from a risky group.
- Monitor new plantings for unexpected spread, volunteering, or aggressive regrowth.
Frequently Asked Questions (FAQs)
Q: How can I tell if an ornamental grass is invasive in my area?
A: Consult your state’s invasive plant council, university extension office, or regional noxious weed lists. Invasiveness can vary by climate and habitat, so always look for locally relevant information.
Q: Are all members of a grass species always invasive?
A: Not necessarily. Some species have both invasive and non-invasive (sterile or low-fertility) cultivars. Always check specific cultivar information and seek recent research on invasiveness before planting.
Q: Can I control invasive grasses by cutting them back regularly?
A: Confined, repeated cutting (especially combined with root removal and mulching) can slow or reduce spread, but may not fully eliminate aggressive rhizomatous species. Persistence is essential.
Q: What should I do if my ornamental grass starts spreading aggressively?
A: Act promptly by removing new shoots, digging up roots and rhizomes, and disposing of material in the trash (not compost). Monitor the area for regrowth and use herbicides if necessary, following label instructions.
Q: Are there any truly safe ornamental grasses?
A: Many native grasses, as well as sterile cultivars of some ornamental species, are well-behaved and non-invasive. Examples include Little Bluestem, Prairie Dropseed, and newer sterile Fountain Grass hybrids.
Quick Reference Table: Invasive vs. Alternative Grasses
| Invasive Grass | Safer Alternative | Notes |
|---|---|---|
| Miscanthus sinensis | Schizachyrium scoparium | Upright native, autumn color |
| Phragmites australis | Panicum virgatum | Native switchgrass, habitat friendly |
| Mexican Feather Grass | Prairie Dropseed | Fine texture, non-invasive |
| Arundo donax | Sorghastrum nutans | Similar height, less aggressive spread |
| Phalaris arundinacea | Muhlenbergia capillaris | Attractive blooms, clumping |
| Pennisetum setaceum | Pennisetum alopecuroides âHamelnâ (sterile form) | Compact, minimal seed set |
Summary Tips for Gardeners
- Assess the risk of invasiveness before planting any ornamental grass.
- Opt for native species and modern sterile cultivars whenever possible.
- Regularly monitor gardens for uncontrolled spread.
- Remove and dispose of invasive grasses responsibly.
More Resources
- Contact your local extension office for the most up-to-date invasive species lists.
- Consult regional plant nurseries and botanical gardens for safe ornamental grass recommendations.
- Follow responsible gardening guidelines to protect both your landscape and the local ecosystem.
References
- https://www.epicgardening.com/invasive-ornamental-grass/
- https://www.youtube.com/watch?v=3c2iz7rRLD8
- https://lakepanoramatimes.com/gardening-landscaping/beware-of-invasive-ornamental-grasses/
- https://www.epicgardening.com/purple-fountain-grass/
- https://shop.epicgardening.com/collections/ornamental-grasses
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