Pampas grass (Cortaderia selloana) is a large, ornamental grass that forms dense clumps of foliage persisting through winter. Although low-maintenance, its vigorous growth requires an annual, aggressive pruning known as a “hard cut.” This pruning maintains the plant’s attractive, fountain-like shape and health. Removing the previous year’s dead material allows for robust new growth and ensures the plant remains vigorous.
Optimal Timing for the Hard Cut
The hard cut should occur in late winter or very early spring, typically February through March, depending on the climate zone. Pruning at this time allows the dry, old foliage to insulate the crown through the coldest months. Cutting too early exposes the plant’s core to potential damage from freezing temperatures and moisture.
The primary timing factor is completing the pruning before new, bright green shoots emerge from the base. Cutting the plant after new growth is visible can damage developing shoots, forcing the plant to expend stored energy on repair. By waiting until the frost danger has passed but acting before active growth begins, you ensure the plant is still dormant. This timing promotes the healthiest return of the plant’s signature plumes in the summer and fall.
Necessary Safety and Preparation Steps
Before cutting, take specific steps to protect yourself and simplify cleanup. The leaves of Cortaderia selloana are tough and have razor-sharp edges, capable of inflicting deep cuts. Therefore, wearing personal protective equipment (PPE) is necessary for this task.
Personal Protective Equipment (PPE)
You must wear heavy-duty leather or cut-resistant gloves, a long-sleeved shirt, long pants, and sturdy footwear to protect your skin. Eye protection is also necessary to shield against flying debris or snapping stems during the cutting process. Before starting, use a long stick to check the base of the plant for nesting wildlife, as the dense foliage often provides winter cover.
Binding the Foliage
A critical preparatory step is to bind the entire clump of grass tightly. Use a strong rope, bungee cord, or heavy-duty strap. Wrap the cord around the foliage multiple times, securing it about a foot or two above where you plan to make your cut. This binding compresses the foliage into a single, manageable bundle, which simplifies the cutting process and prevents the material from scattering.
Technique for Cutting Back Pampas Grass
Once the clump is securely bound and safety gear is donned, focus on removing all of the previous year’s growth. The recommended height for the hard cut is generally between 6 and 12 inches tall above the ground. Cutting back to this height removes the dead material while leaving enough of the crown intact to support vigorous new growth.
Tool Selection
For small or newly established clumps, long-handled loppers are effective, providing the necessary leverage to shear through the tough stems. Larger or older clumps may require a power tool, such as a gas or electric hedge trimmer, to cut through the bundled material quickly. For the most massive clumps, a small chainsaw is sometimes utilized, requiring extreme caution and skill.
After the cut is made, the secured bundle of old foliage can be easily removed and disposed of. Clear away all remaining debris and cut material from the base of the plant. Leaving old, damp material around the crown can create a breeding ground for pests and promote rot, which can weaken or kill the plant.