Pampas grass (Cortaderia species)

Pampas grass is a very tall, clumpy grass with fluffy flower heads. It competes with native vegetation and is a fire hazard.

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How does this weed affect you?

Pampas grass is an environmental weed that:

• outcompetes native vegetation
• is a fire hazard
• harbours vermin
• could threaten forestry.

 It is readily grazed and does not establish in cropping systems.

What does it look like?

Pampas grass grows in clumps about 1 – 1.5 m across, with fluffy flower heads on tall stems. 

There are two species in NSW:

• Common pampas grass (Cortaderia selloana) is up to 6 m tall when in flower. 
• Pink pampas grass (Cortaderia jubata) is up to 4 m tall when in flower. 

Leaves are:

• finely serrated on the edges
• upright and arched if it is common pampas
• arching with leaf tips touching the ground if it is pink pampas
• with a leaf sheath that is:
  • without a line up the middle (midrib)
  • smooth or slightly hairy if it is common pampas
  • very hairy if it is pink pampas.

Flower heads are:

• white, pink or mauve, and present from mid-March to late May (common pampas) 
• pink when young, fading to dark brown, and present from January to late March (pink pampas).

Roots are:

• up to 3.5 m deep
• with rhizomes, a type of underground stem.

Similar looking plants

Common and pink pampas grass looks like New Zealand pampas grass (Cortaderia richardii). New Zealand pampas grass flower heads are yellow to gold, and present from October to January. Its leaf sheath has a distinct line up the middle (a midrib). New Zealand pampas grass does not currently grow in NSW but could invade.

Where is it found?

Pampas grass has naturalised in bushland on the Central Coast and in some areas of the Central Tablelands. It is a major weed in Sydney. There are lots of small populations on the coastal plains of the north coast of NSW. It is spreading across land disturbed by coal mining to the west of Newcastle.

What type of environment does it grow in?

Pampas grass prefers open, sunny locations and can grow in low-fertility soil. It tolerates waterlogging and can infest mangroves, riverbanks, and heathlands. It tends to establish in roadsides, quarries, sand dunes, mine spoil, new forest plantations, and burnt and disturbed bushland.

Maps and records

• Recorded presence of Pampas grass during property inspections (Map: Biosecurity Information System - Weeds, 2017-2020)
  These records are made by authorised officers during property inspections under the Biosecurity Act 2015. Officers record the presence of priority weeds in their council area and provide this to the NSW Department of Primary Industries. Records reflect the presence of the weed on the date of inspection.
  
  
• Estimated distribution of Pampas grass in NSW (Map: NSW Noxious Weed Local Control Authorities, 2010)
  Map shows weed distribution and density estimated by local council weeds officers in 2010.

How does it spread?

By seed

Wind spreads the seed. Garden plants are often the source of new infestations.

Common pampas grass has female and hermaphrodite plants. The female plants produce more seeds if they are pollinated by a hermaphrodite plant.  Pink pampas grass plants are all female and don’t need to be pollinated.

By plant parts

Pampas grasses can spread out via rhizomes (underground stems).

More information

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Control

Successful weed control requires follow up after the initial efforts. This means looking for and killing regrowth or new seedlings. Using a combination of control methods is usually more successful.

To tackle pampas grass:

• check for seedlings across your property as seeds can spread up to 25 km from a parent plant.
• control seedlings as soon as they appear control plants before they set seed as plants can produce up to 100,000 seeds per flower head
• Physical removal is the preferred control method.

Avoid controlling pampas grass in summer to protect native wildlife. In summer, pampas grass can be an important shelter. Snakes such as the diamond python may lay eggs in the grass clumps. 

Pasture management

Grazing

When: while pampas plants are young (stock avoid it once mature)

Follow up: with another control method

Grazing can prevent flowers from developing and setting seed. Only graze where the risk of causing new infestations is low.

Physical removal

When: After rain when soil is moist. It’s easier to get the roots out of the soil.

Follow-up: within 3 to 6 months or when regrowth is visible if following up with a chemical treatment.

Physical removal is ideal wherever possible. 

By hand

Remove plants when they are small. Make sure to remove all the crown and root system, which spreads out from the plants. Wear long sleeves and gloves as protection from the sharp leaves. 

By machine

On larger plants, remove seed heads first and place them in a plastic bag for disposal. Then slash the plant and dig out the crown and roots. 

Chemical control

Use herbicides only where the risk of causing new infestations is low. Do not spray plants stressed by drought or frost. Use follow-up treatments on regrowth. 

For larger plants:

• slash the plant to reduce the foliage
• dispose of the slashed plant material
• allow some foliage to grow back
• spray to wet thoroughly to wet all the leaf surfaces.

You can also use fire to prepare for spraying. Burn plants, allow them to recover, then spray with herbicide. 

Herbicide options

See Using herbicides for more information.

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Glyphosate 360 g/L (Roundup®)
Rate: 1.0 or 1.3 L per 100 L of water
Comments: Actively growing plants, before flowering, spring to autumn. Use higher rate on plants over 1 m high.
Withholding period: Nil.
Herbicide group: M, Inhibitors of EPSP synthase
Resistance risk: Moderate

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Biosecurity duty

The content provided here is for information purposes only and is taken from the Biosecurity Act 2015 and its subordinate legislation, and the Regional Strategic Weed Management Plans (published by each Local Land Services region in NSW). It describes the state and regional priorities for weeds in New South Wales, Australia.

Area	Duty
All of NSW	General Biosecurity Duty All plants are regulated with a general biosecurity duty to prevent, eliminate or minimise any biosecurity risk they may pose. Any person who deals with any plant, who knows (or ought to know) of any biosecurity risk, has a duty to ensure the risk is prevented, eliminated or minimised, so far as is reasonably practicable.
Greater Sydney	Regional Recommended Measure* Land managers mitigate the risk of the plant being introduced to their land. Land managers prevent spread from their land where feasible. Land managers reduce the impact on priority assets. The plant should not be bought, sold, grown, carried or released into the environment.
Hunter Exclusion zone: Upper Hunter local government area. Core infestation area: Port Stephens, Maitland, Cessnock, Lack Macquarie, Newcastle and MidCoast local government areas.	Regional Recommended Measure* Whole region: The plant should not be bought, sold, grown, carried or released into the environment. Exclusion zone: The plant should be eradicated from the land and the land kept free of the plant. Land managers should mitigate the risk of the plant being introduced to their land. Core infestation area: Land managers should mitigate spread from their land. Land managers to reduce impacts from the plant on priority assets.
North Coast	Regional Recommended Measure* Land managers should mitigate the risk of new weeds being introduced to their land. The plant should be eradicated from the land and the land kept free of the plant. The plant should not be bought, sold, grown, carried or released into the environment. This Regional Recommended Measure applies to Cortaderia selloana and Cortaderia jubata (pink pampas grass)
South East	Regional Recommended Measure* Land managers should mitigate the risk of new weeds being introduced to their land. The plant should be eradicated from the land and the land kept free of the plant. The plant should not be bought, sold, grown, carried or released into the environment. Notify local control authority if found. This Regional Recommended Measure applies to Cortaderia jubata (pink pampas grass)
	*To see the Regional Strategic Weeds Management Plans containing demonstrated outcomes that fulfill the general biosecurity duty for this weed click here

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Reviewed 2019