Princess Caroline Grass is a popular ornamental grass cultivar, prized for its visual impact in both landscapes and container plantings. This plant is a hybrid variety of Pennisetum purpureum, commonly known as Napier Grass or Elephant Grass. Gardeners favor it for its rapid growth habit and ability to serve as a bold, upright focal point throughout the warm season. It provides a rich, dark foliage color that maintains its intensity even through the hottest summer months.
Distinctive Characteristics and Appearance
The most notable feature of Princess Caroline Grass is its intensely colored foliage, which ranges from deep burgundy to a near-black purple hue. The leaves are flat, broadly linear, and possess an arching, upright structure, contributing to its fountain-like form. This warm-season grass forms a dense, clump-forming mound that typically reaches a mature height of 3 to 6 feet and can spread up to 5 feet wide in a single growing season.
The coloration depends highly on light and temperature; the foliage tends to deepen into a richer, more saturated purple as summer temperatures climb. The plant is often reported as being sterile or nearly non-flowering, meaning it directs its energy toward producing lush foliage rather than feathery seed heads. In regions that experience frost, the plant will rarely, if ever, develop the purple-black flower spikelets sometimes seen in consistently tropical environments.
Planting Requirements and Ideal Environment
Successful establishment of Princess Caroline Grass begins with selecting the optimal planting location, which must provide ample sunlight. To achieve the deepest, most vibrant purple coloring, the plant requires a full sun exposure, meaning a minimum of six to eight hours of direct sunlight each day. Planting in partial or bright shade will often cause the foliage to “green up,” resulting in a less dramatic, lighter maroon color. This plant is a tender perennial, hardy in USDA Zones 8 through 10, and it thrives in the heat, making it an excellent choice for hot-climate gardens.
The grass is adaptable to a wide range of soil conditions, including clay, loam, and sandy compositions, but the soil must be consistently well-draining. The plant cannot tolerate standing water or perpetually soggy roots, which can lead to crown rot.
Amending heavy soil with organic matter can improve drainage before planting. During the initial establishment period, which lasts for the first few weeks after planting, consistent moisture is necessary to encourage a robust root system. Once established, however, the grass is notably drought-tolerant and requires only occasional watering, benefiting from a deep soak during extended dry spells.
Planting should occur in the spring after the danger of the last frost has passed, allowing the warm-season grass to take advantage of the rapidly rising temperatures. A slightly acidic to neutral soil pH is suitable for this hybrid, and it often performs well in containers where soil conditions are easier to control. When used as a container “thriller,” ensure the pot has large drainage holes to prevent water accumulation at the base.
Seasonal Care and Maintenance
Once Princess Caroline Grass is established, its ongoing care requirements are relatively straightforward, focusing mainly on seasonal preparation and pruning. This grass is a moderate to fast grower and will benefit from being cut back to the ground in late winter or early spring before new growth begins. Removing the dormant, dead foliage helps to tidy the plant and encourages a flush of fresh, vigorous growth for the new season.
Fertilization should be approached with caution, as high-nitrogen feeds can dilute the signature purple pigment of the leaves, causing them to turn a greenish color. Instead of a heavy-duty fertilizer, a single application of a balanced, slow-release granular fertilizer at the beginning of the growing season is sufficient, or simply rely on the nutrients present in rich, amended soil. The plant is generally disease-resistant and is not a favored food source for deer.
In areas north of USDA Zone 8, where winter temperatures drop below freezing, ‘Princess Caroline’ is typically grown as an annual and allowed to die back after the first hard frost.
Overwintering
For gardeners wishing to preserve the plant, it can be overwintered indoors by digging up the entire clump in the fall, trimming the foliage back substantially, and storing the crown in a cool, bright, but frost-free location until spring. Alternatively, in borderline zones, a thick, dry layer of mulch applied over the crown in late autumn can offer enough insulation for the plant to survive a mild winter.