Pampas grass (Cortaderia selloana) is a perennial South American native recognized for its large, showy, feathery plumes. This plant’s impressive size and dense growth habit have made it a popular ornamental choice. Despite its visual appeal, pampas grass is classified as an invasive species in many regions, rapidly displacing native flora. The primary challenge in its removal stems from its extensive, tough root system and large central crown.
Manual Removal Techniques
Removing pampas grass without chemicals requires strenuous labor focused on extracting the entire root crown. The initial step is to cut back the sharp, bladed foliage to expose the base of the plant and reduce the bulk of material. Before starting, wear heavy-duty gloves, long sleeves, and eye protection, as the leaves can inflict deep, razor-like cuts.
Once the plumes have been removed, which should be done carefully to avoid scattering the numerous seeds, cut the remaining blades back to within a few inches of the ground. This clearing provides access to the dense root crown, which is the target for removal. Digging out this crown requires heavy-duty tools such as a sharp shovel, a mattock, or a Pulaski axe.
The goal is to sever the entire root ball from the soil. Any remaining sections of the crown or upper roots can lead to immediate regrowth. For large, established clumps, chop the crown into smaller, more manageable pieces before attempting to lift them out. After the main plant is removed, check the disturbed area meticulously for any remaining root fragments.
Effective Herbicide Applications
Chemical treatment is often the most effective method for controlling large, established pampas grass clumps due to their robust root structure. The most successful approach involves using a systemic, non-selective herbicide, such as concentrated glyphosate. This herbicide translocates throughout the plant to kill the entire root system. A simple foliar spray on the leaves is often ineffective because the waxy coating and dense growth prevent sufficient absorption.
The preferred technique is a cut-and-treat application, which maximizes the herbicide’s effectiveness. First, cut back the plant’s foliage, leaving only a low stump or crown. The concentrated herbicide mixture is then immediately painted or carefully applied directly onto the fresh cuts or the exposed crown. This method ensures the herbicide is absorbed quickly and travels down to the deep roots.
Timing the application is important for successful chemical eradication. The best time for treatment is late summer or early fall, before the first killing frost. During this time, the plant is actively moving resources down to its roots for winter storage. This downward flow, known as translocation, carries the systemic herbicide directly to the root structure. Multiple applications of a high-concentration mixture may be necessary, and always follow the specific dilution and safety instructions provided on the herbicide label.
Safe Disposal and Preventing Regrowth
After the pampas grass has been manually removed or killed by herbicide, proper disposal of the plant material is necessary to prevent its spread and re-establishment. The tough, sharp foliage and stalks can be bundled and disposed of as general yard waste, following local municipal guidelines. Ensure any viable seed heads (plumes) are bagged separately before disposal.
The root crown and large root sections should not be composted in a typical home setting, as they are dense and may still be capable of re-sprouting. Allow these root balls to completely dry out, ideally by turning them upside down to expose the roots to air. Then, dispose of them through a dedicated yard waste or landfill service. Leaving the crown or roots in place risks re-rooting, especially in moist conditions.
Following the removal, the site must be monitored closely for several months to catch any new seedlings or shoots emerging from missed root fragments. Covering the cleared area with a thick layer of mulch or establishing a desirable groundcover plant will help suppress the germination of any remaining pampas grass seeds. Prompt removal of new seedlings is the final action in preventing the aggressive plant from re-establishing itself.