Pampas grass, known scientifically as Cortaderia selloana, is widely recognized for its feathery plumes that stand tall in the late season landscape. These striking white, silver, or pink plumes make the plant popular in ornamental gardening. For most of the growing season, however, this perennial grass presents a vastly different appearance. Understanding the plant’s look before the iconic flower emerges is helpful for identification and garden management.
The Clump and Foliage
Before the plumes appear, Pampas grass is defined by its substantial basal clump, known as a tussock. This dense, mounding structure can easily reach mature dimensions of six to ten feet tall and equally wide, creating a significant presence in the garden. The leaves are long, slender, and arch gracefully outward from the center of the clump, forming a fountain-like silhouette. Their color is typically a deep green to a silvery blue-green, providing an attractive, coarse texture to the foliage mass.
Individual leaves are characterized by their stiff, linear shape and can grow up to six feet in length. These leaf blades possess finely serrated, razor-sharp edges, a trait reflected in the plant’s genus name, Cortaderia, derived from the Argentine word for “cutting.” Caution and protective clothing are necessary when handling or pruning the plant. The sheer volume of this foliage is the plant’s primary feature until flowering begins.
Early Signs of the Emerging Plume
The transition to a flowering specimen begins with the emergence of the culm, or flower stalk. These stalks are rigid and thicker than the surrounding leaf blades, engineered to support the large, dense flower head. They push straight up from the center of the tussock, growing significantly higher than the arching foliage.
Initially, the developing inflorescence is tightly encased within a protective sheath, which appears as a pointed, often green or brownish capsule at the tip of the rising stalk. This sheath covers the immature flower head, shielding the delicate parts as the stalk rapidly elongates. As the flower head matures inside, the sheath splits open, allowing the nascent plume to unfurl its feathery threads, transitioning from a compact spear to a soft tassel.
Seasonal Timing of Flower Development
The pre-bloom state, where the flower stalks are rapidly emerging and elongating, generally occurs after a full season of vegetative growth. This phase typically starts in the late summer, signaling the plant’s readiness to reproduce. The flower plumes then open fully in the late summer to early fall, depending on the specific climate and cultivar.
A plant must achieve sufficient maturity to enter this flowering cycle, usually taking between two and three years from planting before it consistently produces the large plumes. Once the plant is established, the appearance of the rising culms in late summer is a reliable indicator that the feathery blooms are imminent.