The short answer
It depends on where you live. Pampas grass (Cortaderia selloana) is treated as invasive in several regions, including parts of the US West Coast, Hawaii, Florida, Australia and New Zealand. In other regions it is grown as a garden plant without causing much trouble. Check your local invasive plant list or ask a nearby extension office or native plant society before planting.
Where pampas grass is a problem
- California: The California Invasive Plant Council (Cal-IPC) profiles pampas grass, noting that it has escaped into coastal and some inland areas. The related jubata grass (Cortaderia jubata) is considered more aggressive.
- Pacific Northwest: Washington State’s noxious weed board lists pampas grass as a weed.
- Hawaii and Florida: State and university sources describe it as invasive (see ornamental grasses for Florida landscapes for safer picks). The University of Florida’s assessment found it to be invasive, with no recommended uses.
- Australia and New Zealand: Pampas grass is a significant weed problem, including in forestry and conservation areas.
Garden writers also note that regions with milder climates and open, disturbed or sandy ground are the most at risk.
Why it is a problem
- Seeds. Pampas grass spreads mainly by seed, not by underground runners. Each plume can produce many light, wind-blown seeds, though in some places few of those seeds are viable (see the next section).
- Size. Mature plants can be 6 to 13 feet tall and form large, dense tussocks that crowd out native plants.
- Fire. Dry leaves and flower stalks build up in and around the plant. Conservation sources describe this as a fire hazard.
- Sharp leaves. The leaf edges are tough and cutting, so handling the plant takes care.
- Long life. One source gives a plant life of about fifteen years.
Why one pampas grass spreads and another does not
Pampas grass plants are either female or functionally male. The showy, fluffy plumes gardeners love come mostly from female plants. In California, nurseries historically propagated female plants by division, so few seeds were produced, which may explain why the plant spread slowly there in the past.
Things changed when some nurseries began growing it from seed. Seedlings cannot be sexed until they flower, so more male plants entered the mix, and with both sexes around, viable seed increased. Gardening writers therefore advise avoiding male plants if you plant it at all, but you cannot reliably tell the sex of a young plant, which is one reason many agencies discourage planting.
Pampas grass vs jubata grass
Cortaderia jubata is often sold or called “pampas grass” as well. It is generally considered the more aggressive species, since it produces viable seed without needing a male plant. Cal-IPC lists the two species separately, and they can be told apart by features like stem height, plume color and leaf tips. If you are not sure which one you have, an expert ID is worthwhile.
If you already have pampas grass
- Check local rules. Some places restrict planting or require removal.
- Cut the plumes before they release seed. Removing flower heads in late summer, before the seed ripens, limits spread. Bag them rather than leaving them on the ground.
- Wear protection. Use gloves, long sleeves and eye protection when working with it.
- Remove seedlings early. Small seedlings can be pulled by hand or dug up.
- Dig out large clumps. Cal-IPC advises removing the entire crown and the top section of the roots, since pieces left on moist soil can re-root. This is heavy work, so use a mattock or similar tool or hire help.
- Dispose of material carefully. Ask your local authority how to dispose of invasive plant waste.
- Herbicide: Some agencies describe spot herbicide treatments for large infestations. Follow your local agency’s guidance and the product label if you go this route.
What to plant instead
If you want a similar look without the risk, consider these, and check local suitability first:
- Giant wildrye (Elymus condensatus) is suggested as a native alternative in California.
- Pink muhly grass (Muhlenbergia capillaris) and Fakahatchee grass (Tripsacum dactyloides) are suggested in Florida. Muhly grass has airy pink plumes and grows about 3 feet tall. See how to grow pink muhly grass.
- Miscanthus cultivars offer tall, plume-topped clumps. Check local status, as some are flagged in parts of the eastern US. See Miscanthus vs Pennisetum.
- ‘Karl Foerster’ feather reed grass gives a strong vertical accent at a smaller scale. More ideas are in grasses as specimen plants and focal points.
- Switchgrass, big bluestem and Indian grass are native options for tall plantings in many parts of North America. See tall ornamental grasses for privacy screens.
For more plants that stay where you put them, see our list of non-invasive ornamental grasses and the wider guide to types of ornamental grasses.