Purple fountain grass (Pennisetum setaceum 'Rubrum') is a showy dark reddish-purple ornamental grass that will grow to a height of 4 to 6 feet at maturity. In mid-summer, purple fountain grass will produce feathery, reddish-purple plumes that that rise above the foliage, putting on a show that lasts until autumn. An adaptable warm weather plant that grows with virtually no maintenance, purple fountain grass is a warm weather plant, hardy in USDA zones nine to 11. In cooler climates, treat purple fountain grass as an annual and replant every spring.
Water purple fountain grass only during extended dry weather; purple fountain grass is a drought-tolerant plant that thrives in areas with very little rain.
Apply a slow-release fertilizer in early spring to ensure healthy growth throughout the season. Use 1/2 to 1 lb. of granular fertilizer for each 100 feet of growing space.
Spread 2 to 3 inches of mulch such as pine needles or shredded bark around the plant. Mulch will help to discourage weeds and will keep the roots cool.
Cut purple fountain grass down to a little less than 5 feet in early spring to keep the plant looking neat. The grass will grow back quickly.
Divide purple fountain grass to improve the appearance of the plant if the center of the grass begins to look old and unproductive. Divide the grass in early spring before new growth appears. Dig the entire clump and use a sharp knife or a shovel to divide the plant into smaller sections. Discard the old, woody center of the plant. Be sure each section has four to five shoots and a healthy root section. Plant the divided sections in soil that has been prepared ahead of time.