Cortaderia selloana, commonly known as pampas grass, is a large, ornamental perennial grass known for its dramatic plumes. This species forms dense, towering clumps of foliage that can reach heights of ten feet or more. Many worry that the severe trimming required to manage this plant will permanently damage or kill it. Cutting pampas grass back hard is not only safe but is a necessary component of its annual care cycle.
The Resilience of Pampas Grass to Cutting
Cutting pampas grass will not kill the plant because it is a perennial that stores energy in its underground structure. The plant survives the winter and aggressive trimming by relying on a robust root system and a protected growth point called the crown. The crown is the dense base of the plant, situated just at or below the soil line, where all new growth originates.
The foliage that is cut back is dead material from the previous season, similar to how deciduous trees lose their leaves. This superficial dieback is a natural part of the plant’s life cycle. Annual cutting back mimics this process, clearing the way for new shoots to emerge from the crown in the spring. As long as the crown remains intact, the plant will reliably regenerate with fresh, vigorous growth.
Differentiating Pruning and Plume Harvesting
Pampas grass is cut for two primary reasons, each with a different timing and purpose. The first is a full cutback, known as annual hard pruning, which involves cutting the entire clump of old foliage back to within six to twelve inches of the ground.
Hard pruning is ideally timed for late winter or very early spring, just before new growth appears. Removing the old foliage at this time allows light and air to reach the emerging shoots, preventing the center of the plant from becoming choked with dead material. This maintenance cut encourages a clean, healthy, and symmetrical clump for the coming season.
The second type of cutting is harvesting plumes, which removes the decorative flower stalks. These plumes are typically cut in the fall when they are fully mature. Harvesting the plumes allows them to be used indoors for ornamental purposes and helps prevent the plant from scattering its seeds. This is a selective cut that does not involve removing the main body of foliage.
Essential Cutting Techniques for Healthy Regrowth
Performing a hard prune requires preparation, focusing on safety due to the abrasive nature of the foliage. The leaves of Cortaderia selloana have razor-sharp edges. Therefore, wear thick, cut-resistant gloves, long sleeves, long pants, and protective eyewear before beginning work.
An effective technique for managing the large bulk of the foliage is to first use twine or a ratchet strap to tie the entire clump together. This cinching action compacts the old leaves into a manageable bundle, making the cutting process easier and reducing debris. Once bundled, use long-handled loppers or a pruning saw to cut across the bundle, leaving a tuft of foliage six to twenty inches high.
The most important step is to ensure the cut is made well above the crown. Damaging the crown can seriously injure or kill the plant, so cutting must occur high enough to avoid this sensitive region. After the cut is complete, clear away all debris to expose the base of the plant, which promotes better air circulation and allows new spring growth to emerge unimpeded.