Avoid Planting These 11 Invasive Ornamental Grasses

Choose low-spread foliage that supports wildlife and keeps your garden thriving.

By Sneha Tete, Integrated MA, Certified Relationship Coach

Created on Sep 4, 2025

Choose low-spread foliage that supports wildlife and keeps your garden thriving.

Ornamental grasses have become increasingly popular in garden landscapes for their resilience, low-maintenance appeal, and visual versatility. Yet some of these seemingly ideal choices are aggressive invaders that disrupt local ecosystems and create logistical headaches for gardeners. This article explores what makes ornamental grass invasive, identifies eleven major species to avoid, and suggests eco-friendly alternatives for a balanced, thriving garden.

What Is an Invasive Ornamental Grass?

An invasive ornamental grass is any non-native grass species that spreads rapidly, outcompetes local plants, and can dominate landscapes and natural habitats. These grasses often thrive outside their native range because they face few pests, predators, or diseases that would otherwise keep their populations in check. A grass is considered invasive if it:

Outcompetes native plants for sun, water, and nutrients
Spreads aggressively via rhizomes or abundant seed production
Requires intensive labor to remove or control
Reduces biodiversity and damages ecological balance

The most problematic grasses often spread by underground rhizomes, which persist and regenerate even after physical removal, causing continuous issues for gardeners and homeowners. Invasive ornamental grasses are particularly difficult to contain and can encroach upon areas where they are unwanted or even overwhelm entire garden beds.

Why Are Ornamental Grasses So Popular?

Homeowners and landscape designers favor ornamental grasses for their:

Drought tolerance
Perennial growth
Low maintenance needs
Striking visual appealâfrom arching fronds to feathery plumes

These traits, however, can also make them formidable invaders if gardeners neglect to consider local biodiversity and ecosystem health.

Criteria for Invasiveness: When Does Grass Become a Problem?

Several factors contribute to the invasiveness of ornamental grasses:

Rapid reproduction: Many species set enormous numbers of seeds that germinate easily.
Rhizomatic spread: Underground runners allow these plants to rebounce vigorously after attempts at removal.
Lack of natural controls: In non-native habitats, local wildlife and pests may not recognize or utilize the grass, allowing it to grow unchecked.
Displacement of native flora: Invasive grasses outcompete regional plant species, harming pollinators and wildlife that rely on native plants.

11 Invasive Ornamental Grasses to Avoid

Although certain regions might tolerate some of these species, most are regarded as invasive across the United States and in similar temperate climates. The following table summarizes their characteristics and the risks they pose to gardens and natural spaces:

Common Name	Scientific Name	Spread Method	Risks
Johnson Grass	Sorghum halepense	Rhizomes & seeds	Outcompetes crops; persistent rhizomes make removal tough
Bamboo	Bambusa spp.	Rhizomes	Extremely rapid spread; hard to control or eradicate
Pampas Grass	Cortaderia selloana	Seeds	Invades coastal areas; fire risk in some climates
Cogongrass	Imperata cylindrica	Rhizomes & seeds	High fire risk; crowds out native plants
Giant Reed	Arundo donax	Rhizomes	Disrupts water flow; forms dense stands in wet areas
Weeping Lovegrass	Eragrostis curvula	Seeds	Rapid colonizer; threatens habitat diversity
Mexican Feather Grass	Nassella tenuissima	Seeds	Self-seeds prolifically; hard to remove
Japanese Silver Grass	Miscanthus sinensis	Seeds	Can escape cultivation; invades open spaces
Chinese Fountain Grass	Pennisetum alopecuroides	Seeds	Naturalizes quickly; crowds out natives
Hardy Pampas Grass	Erianthus ravennae	Seeds	Spreads rapidly in wetlands and riparian zones
Onion Grass	Romulea rosea	Bulbs	Very deep roots; difficult to remove

Problems Caused by Invasive Grasses

Aggressive spreading makes them tough to control and can choke out garden beds, lawns, or natural vegetation
Reduces biodiversity by crowding out native plant species and disrupting food sources for local wildlife
Alters soil chemistry and water availability for other plants in the area
Increases fire risk due to dense, dry foliage in fire-prone regions
Escapes cultivation and invades neighboring properties or wild areas

How Do Invasive Grasses Spread?

Most invasive ornamental grasses use two main strategies:

Rhizomes: Underground stems that sprout new shoots and regenerate even after partial removal.
Seed dispersal: Wind, water, wildlife, and humans help unwanted grasses colonize new areas.

As a result, simply pruning or digging out the top of the plant rarely solves the problemâthe roots and seeds continue to propagate, leading to recurring infestations.

Recognizing Invasive vs. Non-Invasive Grasses: Whatâs the Difference?

Feature	Invasive Grass	Non-Invasive Grass
Growth Habit	Aggressive, widespread	Clumping or slow spread
Seed Fertility	Very high; prolific self-seeder	Low or sterile cultivars
Effect on Ecosystem	Diminishes biodiversity	Compatible with local flora
Maintenance	Intensive removal required	Low maintenance, easy to contain

Ornamental Grasses With Non-Invasive Cultivars

Not all ornamental grasses are problematic. Plant breeders have developed new cultivars that are sterile, lower-fertility, or specifically bred not to self-seed or spread aggressively. These eco-friendly variants focus more energy on foliage and flowers, offering the same aesthetic benefits without the risk of unchecked colonization.

Sterile Fountain Grass (Pennisetum setaceum âRubrumâ): This variety does not produce viable seed and is safe to plant in most regions, particularly California.
Clumping Grasses: Species that grow in compact bunches rather than spreading runners are typically well-behaved choices.
Regionally Native Species: Choose grasses native to your locality, as these are naturally part of the ecosystem and support wildlife.

Tips for Selecting Non-Invasive Grasses

Consult local nurseries or extension services for advice on native and non-invasive options
Avoid species listed on your state or regionâs invasive plant register
Choose cultivars labeled as sterile or non-fertile
Consider how the plant fits into local pollinator and wildlife food webs

Eco-Friendly Alternatives to Popular Invasive Grasses

If you want the texture and movement of ornamental grasses without ecological risk, try these alternatives:

Switchgrass (Panicum virgatum): A North American native with beautiful seed heads and clumping growth
Little Bluestem (Schizachyrium scoparium): Striking blue-green foliage, autumn color, and wildlife benefits
Pennisetum setaceum âRubrumâ: Sterile purple fountain grass with vivid fronds; easy-care and non-invasive
Blue Fescue (Festuca glauca): Compact clumps and silvery-blue foliage ideal for edging or borders

These alternatives provide similar form and function without threatening your landscape or native habitats.

Maintenance and Control: Preventing Invasive Grass Spread

If you inherit invasive grasses or discover them in your garden, follow these steps for responsible management:

Remove entire root masses, including rhizomes and bulbs
Dispose of all plant material in the trash, not compost, to prevent re-rooting
Mulch heavily to suppress regrowth, but monitor for shoots
Install physical root barriers for any grasses suspected of aggressive spread

Dividing and Maintaining Non-Invasive Varieties

Eco-friendly ornamental grasses, like purple fountain grass, may require periodic division to maintain vigor. Division is easiest during early spring or fall and involves:

Cutting back leaf height
Excavating the root mass from the ground
Slicing root ball into sections with both root and plant tissue
Replanting as you would a new specimen

Unlike invasive species, these grasses are easy to keep tidy and well-contained.

Frequently Asked Questions (FAQs)

Q: What makes an ornamental grass invasive?

A: Ornamental grasses are considered invasive if they spread rapidlyâtypically via rhizomes or prolific seedingâand outcompete native plants, reducing biodiversity.

Q: Are all ornamental grasses invasive?

A: No, many ornamental grasses are non-invasive, especially clumping cultivars or sterile varieties. Always check for labels indicating non-fertility or eco-friendly breeding.

Q: Can invasive grasses be safely removed?

A: Removal can be challenging, as many species regenerate from rhizomes or deep roots. For best results, dig up the entire root mass and dispose of it in the trash, never in compost.

Q: Are there ornamental grasses that are safe to plant?

A: Yes! Native clumping grasses like switchgrass and little bluestem, as well as sterile purple fountain grass (Pennisetum setaceum âRubrumâ), are excellent non-invasive choices.

Q: How can I tell if a grass is invasive in my region?

A: Check with local agricultural extension offices or state invasive plant lists. Invasiveness can depend greatly on climate, soil, and local ecosystem conditions.

Summary Table: 11 Ornamental Grasses to Avoid

Species	Main Risks	Spread Method
Johnson Grass	Persistent rhizomes, crop invader	Rhizomes & seeds
Bamboo	Rapid underground spread	Rhizomes
Pampas Grass	Dense stands, fire risk	Seeds
Cogongrass	Biodiversity threat	Rhizomes & seeds
Giant Reed	Riparian area invader	Rhizomes
Weeping Lovegrass	Habitat colonizer	Seeds
Mexican Feather Grass	Self-seeding nuisance	Seeds
Japanese Silver Grass	Escapes cultivation	Seeds
Chinese Fountain Grass	Crowds out natives	Seeds
Hardy Pampas Grass	Wetland colonizer	Seeds
Onion Grass	Deep roots, hard to eradicate	Bulbs

Responsible Gardening: Protect Your Landscape and Local Ecosystem

A beautiful landscape and a healthy ecosystem can go hand in hand. By avoiding invasive ornamental grasses and adopting eco-friendly alternatives, gardeners contribute to regional biodiversity and reduce maintenance headaches. Carefully research plant choices, consult local experts, and opt for native or sterile cultivars to enjoy the benefits of ornamental grasses without risk.