Pampas grass (Cortaderia selloana) is a distinctive ornamental plant prized for its dramatic size and voluminous, feathery plumes. Its imposing presence makes it a popular choice for creating a striking focal point or a natural screen in larger garden settings. Understanding the plant’s substantial mature dimensions is the primary consideration for homeowners planning their landscape. This impressive growth habit often leads to questions about the final size and how to manage it within a defined space.
The Dimensions of Mature Pampas Grass
The standard variety of pampas grass forms dense, substantial clumps of foliage. A typical mature plant will reach a height between 8 and 12 feet, with a spread ranging from 4 to 8 feet across the base. The leaves themselves are long, arching, and have razor-sharp edges, which must be considered when planting near walkways or play areas.
The plant’s overall height is significantly increased by its showy flower plumes, which rise well above the basal foliage. These silvery-white plumes, which are more common and impressive on female plants, can add an extra two to four feet to the total height. Pampas grass is a fast-growing perennial that achieves its maximum size relatively quickly. It generally takes only three to four years for a young plant to reach its full, mature dimensions.
Size Variance Among Popular Cultivars
Not all pampas grass plants achieve the towering dimensions of the standard species. Specific named varieties, or cultivars, have been developed to offer different sizes, allowing gardeners to gain the plant’s aesthetic appeal without the associated space commitment. This size variation is a key factor when selecting pampas grass for a smaller yard.
One of the most popular compact options is the cultivar ‘Pumila,’ frequently sold as dwarf pampas grass. This variety typically grows to a manageable height of 4 to 6 feet, with flower spikes extending to about 6 to 7 feet tall. Another well-regarded cultivar is ‘Sunningdale Silver,’ which often stays on the lower end of the species’ range, reaching heights of around 8 feet. Choosing a cultivar like ‘Pumila’ allows the dramatic texture and plumes of pampas grass to be used in mid-sized garden beds where the standard species would overwhelm the space.
Managing Growth and Size
Managing the size of an established pampas grass clump requires routine maintenance due to its rapid growth. The most effective method for size control is a severe annual pruning, performed in late winter or early spring before new growth begins. This involves cutting the entire foliage clump back to a height of approximately 12 to 18 inches above the ground.
This heavy cut removes the large, dense mass of old leaves and promotes fresh, vigorous growth for the coming season. Due to the sharpness of the leaf edges, it is important to wear thick gloves, long sleeves, and eye protection during this task.
Over many years, the center of the plant’s root crown can become old and dense, which may lead to a decline in vigor. When this occurs, the entire clump may need to be divided to physically reduce its footprint and rejuvenate the plant. Using a sharp spade or saw to cut sections from the outer, healthier parts of the clump for replanting will effectively manage the plant’s overall density and spread.