How to Plant, Grow, and Care for Purple Fountain Grass

Purple fountain grass is an umbrella term covering a handful of Cenchrus setaceus cultivars on the reddish-bronze side of the color spectrum. It is a clumping ornamental plant with narrow arching leaves and plumes of feathery, bottlebrush flowers.

Formerly Pennisetum setaceum, this species is a tender perennial that will not survive winters with extreme temperatures. Hardy only down to zone 9, treat it like an annual in cold regions. It’s beautiful as a colorful container garden thriller or landscape accent. 

In warmer regions, plant purple fountain grass for contrast and a natural aesthetic. It spreads easily by seed and poses a fire risk in some parts of the world, so be sure to check your local invasive or plant watch list before growing this one in a southern climate.

Read on for a closer look at this species and its unique personality. We’ll discuss this plant’s history, growing preferences, maintenance needs, and problem areas. We’ll also spotlight some of the cultivars included in the purple fountain grass family. 

Characteristics

Purple fountain grass leaves are long and thin, with a rough surface and densely packed, fine hairs. They average between one and three feet long, standing firm in the landscape in shades of purple, red, and bronze. The foliage holds its color all season and does not wilt. Its form is rounded, wide-spreading, and rigid. 

In late summer to early fall, it sends up sturdy flower spikes with terminal racemes in hues of pink, cream, purple, and red. Blooms are elongated and feathery in texture, arching and nodding outward in a fountain shape. They contain seeds that attract birds and self-spread freely. 

This ornamental grass is hardy in zones 9-11 and grows best in full sun to partial shade locations. It tolerates a wide range of soil conditions and is very drought tolerant, which makes it either a treasure or a threat, depending on where you live. 

History & Cultivation

Native to the scrubby, arid regions of Africa and Western Asia, purple fountain grass seeds were introduced to North America in the late 1800s. While this herbaceous perennial was being sold commercially, it was also spreading naturally throughout parts of Arizona and Southern California and quickly became a nuisance plant. 

Currently, the National Park Service designates fountain grass as an invasive species in Hawaii, California, Nevada, and Arizona, but it remains popular and relatively non-threatening in regions with cold, hard winters. Botanists contribute to its popularity by creating fountain grass cultivars with red-purple leaves, and there are dozens of varieties sold in garden centers today. 

Propagation

Cultivars are hybrid plants that will not reproduce true to seed. If harvested or allowed to self-sow, new plants will likely have the characteristics of one of the tan, naturally-colored fountain grass species from which they were derived. To generate a clone of your existing variety, use the process of division. Here are the steps:

Division

Planting

Plant in spring after all danger of frost has passed or in fall, about six weeks before you expect your first frost. This gives roots a chance to establish without being stressed. The following planting instructions apply to both nursery-grown plants and newly divided transplant sections:

How to Grow

Purple fountain grass is very easy to grow when its basic needs are met. Here’s a breakdown of its light, water, soil, climate, and fertilizer preferences:

Light

Plant in a location with full sun, if possible. This means at least six hours of direct sunlight per day. If full sun is not an option, fountain grass tolerates partial shade locations (between 4 and 6 hours of direct sun per day) but nothing less. 

Water

Choose a location or container that drains well for the healthiest outcome. Site your grass in a berm or high area where its roots and crown will not be flooded by standing water, since this invites disease and rot. Soil should be moist but not puddly. 

During its first year of growth, or if you’re growing it as an annual, be sure it’s getting an inch of water per week. Monitor your local precipitation levels, use a soil moisture gauge, or use a finger poke to determine if the soil is dry and needs supplemental watering. Use a soaker hose or watering wand to direct water at soil level, rather than leaves. 

Soil

This plant tolerates a wide range of soil types but grows best in loam, which is a mixture of sand, clay, and humus or silt. Take a soil test to determine your bed’s exact makeup, or use your judgment to determine if a potential bed needs amendment.

If the soil is compacted and hard to work with, add some compost or organic material to loosen the structure. If soil is too sandy, peat moss, vermiculite, and composted manure can help slow drainage and achieve a stickier, more hospitable consistency. 

Climate

Fountain grass is a warm-weather plant that enjoys summer temperatures between 75 and 85 degrees Fahrenheit (24-29 degrees Celsius). While it is known for being the most cold-tolerant in the genus, it will not return predictably in zones below 9. In those regions, it enjoys a long, colorful season as an annual but will probably not come back next year unless temperatures are unseasonably warm. 

Fertilizing

This ornamental grass does not need supplemental feeding to look its best under ideal growing conditions. A fertilizer application will not likely affect its overall health and appearance, but it also won’t hurt it. If you’re feeding a landscape bed or mixed container that includes purple fountain grass, use an even NPK ratio (10-10-10) for best results. 

Maintenance

Known for being prolific and low-maintenance, it takes care of itself for the most part. If you’re growing it as an annual, you shouldn’t need to do much of anything (outside of meeting its water and sun exposure needs) to keep it looking good all season. In zones 9-11 where this genus is perennial, cutback and division are the only maintenance tasks it requires. 

Cutback

Once a year, cut it down to the crown to remove dead foliage and encourage new growth. Many gardeners (and their bird friends) enjoy the winter foliage and leave it alone until spring, but the timing of this task is a matter of preference. Beginning in either spring or late fall, use clean, sharp hedging shears to cut fountain grass down to about eight inches above crown level. 

Division

Every three or four years, purple fountain grass begins to crowd itself out. A hole or dead spot in the middle of the plant’s crown, as well as reduced flowering, are indications that it’s time to perform this maintenance task. Here are the steps:

Varieties

The umbrella term ‘purple fountain grass’ refers to any fountain grass cultivar with foliage on the red or purple side of the color wheel. Since homeowners and landscape designers are attracted to the contrast red leaves provide in an otherwise green landscape, the horticulture industry has answered the call with dozens of options. 

Not all growers and distributors have adapted to the genus change from Pennisetum to Cenchrus, so you may see varieties tagged either way in nursery and website descriptions. Here is a sampling of the most popular cultivars: 

Rubrum

	botanical name Cenchrus setaceus ‘Rubrum’
	sun requirements Full sun
	height 3-5 feet
	hardiness zones 9-11

This is the quintessential variety and the one you’re most likely to encounter in stores and landscapes. It’s large and showy, with dense burgundy leaves and big plumes of feathery racemes in late summer.

Young flowers are typically maroon but eventually mature to a creamy rose color. ‘Rubrum’ is appreciated in horticulture circles for its relative sterility. Although its seeds disperse in the wind after fertilization occurs, they rarely self-sow in the wild. 

Fireworks

	botanical name Cenchrus setaceus ‘Fireworks’
	sun requirements Full sun
	height 2-3 feet
	hardiness zones 9-10

This mid-sized, showy cultivar has vibrant red leaves with contrasting midribs in dark burgundy or forest green. Leaf bases and margins are often variegated in shades of cream.

The flowers resemble fox tails and droop slightly at the end of firm, arching stems. They emerge maroon but mature to a tan color toward the end of the season. ‘Fireworks’ will hold its color all year in zones 9 and 10 and does not self-spread easily. 

Red Riding Hood

	botanical name Cenchrus setaceus ‘Red Riding Hood’
	sun requirements Full sun to partial shade
	height 1-2 feet
	hardiness zones 9-10

For a smaller-scale pop of color in the landscape or container, ‘Red Riding Hood’ is a great option. Maxing out at two feet tall and wide, this compact cultivar has narrow, arching leaves in a deep shade of burgundy. Its long, bristled flowers are rose pink to maroon in hue. They open in June and hold their color through the fall. 

Common Problems

Purple fountain grass has very few problems with pests and diseases. Improperly spaced plants or improperly watered plants may have some fungal issues, but these are aesthetic and temporary. If you notice a white powdery film on the foliage, prune off the affected leaves as close to the crown as possible, and don’t worry about it. To prevent these issues from recurring, direct irrigation at the soil, rather than the leaves, and space it generously from other plants. 

Leaves may also get munched by slugs or snails in wet and humid conditions, but again, it’s nothing life-threatening. If the leaves are shredded slightly at the margins or punched with bite-sized holes, look for slimy trails on their undersides to indicate the presence of slugs or snails.

Since these critters are most active at night, visit the garden after dark and pick them off by hand or blast them off with a hard spray from your hose. You can also set beer traps in the soil nearby to lure them away. Affected or unsightly leaves can be pruned off near the crown to keep plants tidy. 

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