The purple fountain grass, Pennisetum setaceum ‘Rubrum’, is a popular annual grass celebrated for its deep burgundy color and gracefully arching form. While often used as a focal point in garden beds, it is especially striking when planted in containers. Container gardening allows for portable, vibrant displays that feature its fountain-like habit and soft, purple-red flower plumes. Successful container planting requires selecting companion plants that complement the grass aesthetically and thrive under the exact same growing conditions.
Understanding Purple Fountain Grass Needs
The success of any mixed container planting depends on matching the cultural requirements of all the plants involved. Pennisetum setaceum ‘Rubrum’ is a warm-season grass that prefers the hottest part of the year for peak performance. It requires full, direct sun exposure for at least six hours daily to ensure its deep foliage color is fully saturated. Insufficient sunlight will cause the signature burgundy color to fade to a dull green-bronze.
The grass favors a light, moderately fertile, and well-draining soil composition, which is particularly important in a container setting. Although it tolerates drought once established, a container environment requires more consistent moisture than in-ground planting. This prevents the roots from overheating and drying out. Companion plants must, therefore, be sun-loving varieties that appreciate regular watering but cannot tolerate soggy, waterlogged conditions. The grass benefits from regular, balanced fertilizer application to maintain vigorous growth and rich color, a need that should be shared by its container mates.
Design Strategy for Container Arrangements
Purple fountain grass naturally serves as the vertical centerpiece, or “thriller,” of a container arrangement due to its height, texture, and commanding color. The flowing, upright habit creates a dynamic focal point that draws the eye upward. Companions must be chosen to provide visual balance and cover the base of the grass, which can sometimes look sparse in a pot.
The arrangement requires two other categories of plants for a full, balanced look: “fillers” and “spillers.” Fillers are mounding plants that occupy the middle ground, adding mass and contrasting foliage or flower color against the grass’s fine texture. Spillers are trailing plants that cascade over the container’s edges, softening the pot’s hard lines and visually connecting the arrangement to the surface below.
Color selection is a powerful tool to enhance the deep burgundy of the Pennisetum. Highly contrasting colors, such as lime green, chartreuse, silver, or bright yellow, create a vibrant, high-energy look. For a more sophisticated effect, companion plants can be chosen in shades of deep purple, plum, or magenta, complementing the grass in a monochromatic scheme. Texture is also important; the thin, linear blades of the grass look best when paired with plants that have broad, rounded, or variegated leaves.
Companion Plant Recommendations for Sun and Color
Selecting the right filler plants is the first step in building the container’s midsection and adding structural contrast. Sun-tolerant Caladiums (like the ‘Heart to Heart’ series) offer broad, striking leaves in shades of white, pink, or red that contrast sharply with the grass’s fine texture. For continuous bloom, Lantana is an excellent choice; its clusters of flowers in warm colors like yellow, orange, or bright pink thrive in the same heat and sun conditions as the grass.
Another superb filler option is the Petunia, especially vigorous, sprawling varieties like the Supertunia Vista series, which produce a blanket of color in pink, magenta, or violet. These heat-tolerant bloomers easily fill the space around the base of the grass. The silvery-white foliage of Dusty Miller (Senecio cineraria) provides a cool, metallic contrast that makes the purple foliage appear richer and deeper.
For the spiller role, the Sweet Potato Vine (Ipomoea batatas) is unmatched in its vigor and range of colors. Varieties like ‘Margarita’ or ‘Sweet Caroline Sweetheart Lime’ with chartreuse foliage provide a dramatic color clash against the burgundy grass. For deeper contrast, dark purple-black cultivars such as ‘Sweet Caroline Raven’ create a sophisticated, near-monochromatic look.
Creeping Jenny (Lysimachia nummularia ‘Aurea’) is a fast-growing spiller that offers small, rounded, bright gold leaves, creating a bright splash of color over the edge. Another excellent flowering trailer is Calibrachoa, or Million Bells, which produces masses of tiny, petunia-like flowers in nearly every color, including deep cherry red or bright yellow. These companions offer diverse textures and colors while sharing the sun-loving, moisture-consistent environment that allows Pennisetum setaceum ‘Rubrum’ to flourish.