Purple Fountain Grass in Northern Climes

Purple fountain grass in bloom with lavender flowers in background.
David Beaulieu

Purple fountain grass is not very cold-hardy, but it is well worth growing in the North, even if you can enjoy it for only two seasons out of the year. The only argument against growing it is that it is more expensive than other plants grown as annuals. But if you can afford it, this plant will give you a showy, multi-faceted display.

Taxonomy and Botany of Purple Fountain Grass

Plant taxonomy classifies purple fountain grass as Pennisetum setaceum Rubrum. Because Rubrum means "red" in Latin, some people use "red fountain grass" as the common name. Rubrum is the cultivar name.

This clump-forming ornamental variety is a tropical plant. Consequently, those who live in cold climates usually treat it as an annual.

Features of Purple Fountain Grass

Some plants are primarily foliage plants, grown for their luscious leaves. Other plants earn their keep based on their floral color. Still others offer us attractive berries, seed heads, etc. But, sometimes, we get the whole package in one plant. Such is the case with purple fountain grass, so called because arching spikes of purplish flowers gracefully spray out of its mass of long, slender, burgundy-colored leaves. Pennisetum setaceum Rubrum reaches a height of 3 to 5 feet with a spread of 2 to 4 feet. The plant typically blooms in July. Its purplish flower spikes are followed by burgundy or purplish-tinged seed heads, which are soft to the touch and cry out to be swayed by an autumn breeze.

Deer pests usually leave it alone, qualifying this plant as a deer-resistant ornamental grass. Although the species from which this cultivar was developed is considered an invasive plant in parts of the U.S., the cultivar is not considered invasive.

Planting Zones, Overwintering Tips

Indigenous to Africa and southern Asia, purple fountain grass is best grown in zones 9 to 10. Those in colder zones will have to make do with enjoying its vivid color and striking, vase-shaped form in summer and fall, unless they don't mind going through the trouble of overwintering it indoors (in which case it would make sense to grow it as a container plant, so that you could move it inside easily when the time comes).

If you do wish to overwinter the plant, you have two options:

  • Treat it as a houseplant. In this case, you'll want to locate it in a relatively cool room in your home and give it sunshine.
  • Store it in a cool (but not freezing) location, such as a cellar.

Either way, water sparingly, but don't let the soil in the container totally dry out at any point. You can return it to the outdoors next spring at the same time that you see people planting annuals in your area.

Sun and Soil Needs, Uses in Landscaping

Grow Pennisetum setaceum Rubrum in full sun. Like so many plants, this ornamental grass craves a well-drained soil. If you are cursed with a soil that is somewhat waterlogged, try a sedge grass instead. In fact, purple fountain grass is considered a drought-tolerant ornamental grass.

Its beauty makes it popular as a focal point in a mixed planting, often in container gardens. But people will also mass several of the plants together (in a border planting, for example). Conversely, you can let them stand alone as specimen plants. Some like to use them to jazz up a foundation bed for the summer. Grouped with plants of a coarser texture, they can create a striking contrast.

Because its autumn seed heads are so attractive, the plant is, like maiden grass, very useful in fall flower gardens. The feathery seed heads (or "plumes") can later be cut for dried flower arrangements.

Cultivars, Other Kinds of Pennisetum

Another cultivar of the species, Pennisetum setaceum is Fireworks. The leaves are variegated, with burgundy in the middle and hot pink at the edges. It grow 3 to 6 feet in height, with a spread of 1 to 3 feet. It is a perennial in zones 9 to 10. But P. setaceum is not the sole species in this genus. Fortunately for Northerners, P. alopecuroides can be grown as a perennial in zones 5 to 9. Types of P. alopecuroides include the following:

  • Burgundy Bunny stands 16 inches tall, with a spread of 16 inches. Its foliage has hints of red in summer, but this color intensifies to a deep reddish-purple in fall. The flower heads are buff-colored.
  • Little Bunny, at just 12 inches tall (with a slightly greater spread), gives you a shorter option. The trade-off is that it lacks the colorful foliage of Burgundy Bunny. This is another plant with buff-colored flowers.

Companion Plants for Purple Fountain Grass

Many types of plants will suggest themselves as companions to grow alongside purple fountain grass, depending on your particular tastes. The only limiting factor is that you must choose other full-sun plants.

In terms of a color scheme, some gardeners will wish to "paint" with colors from the same side of the color wheel, using plants with pink flowerslavender-colored flowerspurple flowers, or blue flowers, or plants with a similar foliage color. For example, Northerners could grow Panicum virgatum Apache Rose together with their purple fountain grass during the summertime (the former, a perennial in zones 4 to 9, will even survive the winter). Apache Rose has an erect, clump-forming growth habit and is classified as a medium-sized ornamental grass. It attains a mature height and spread of 40 to 48 inches and 26 to 30 inches, respectively, giving it a columnar form. It will grow taller in the South than in the North. As a warm-season grass, its growth rate will not take off until late spring or early summer (depending on where you live). It bears blade-shaped leaves that are grayish-green during the early summer months. In late summer, it produces panicles of small flowers that turn rosy-pink in color, as does a goodly portion of the foliage.

This rosy-pink coloration is the reason behind the "Rose" in its cultivar name and makes it a good companion, visually, for purple fountain grass.

But purple fountain grass also looks wonderful with contrasting yellow flowers. You can also achieve a striking composition by striving for a contrast in texture, growth habit, and plant height. The leaves of cannas, for example, will contrast nicely with those of purple fountain grass. If you're growing your purple fountain grass in a pot, move the container in front of oakleaf hydrangea in the fall: The purplish fall foliage and contrasting texture of the latter will provide an effective backdrop. And for the foreground, install a short plant with a growth habit that contrasts with the upright purple fountain grass, for example, annual lobelia or blue fescue.