Purple Fountain Grass (Pennisetum setaceum ‘Rubrum’)

Of all the ornamental grasses, of which there are many, purple fountain grass (Pennisetum setaceum ‘Rubrum’) is probably one of the most popular. The purple or burgundy-colored foliage and soft, fuzzy-like blooms (which are followed by purplish seedheads) make a bold statement in the garden—on their own or grouped with other plantings. Growing purple fountain grass is easy and requires little maintenance once established.

I. Appearance and Characteristics

While purple fountain grass is known as a perennial, it is actually considered a tender perennial. This ornamental grass cannot survive cold winters and is hardy only in USDA Plant Hardiness Zones 9 and warmer (though in Zones 7-8 it can sometimes reappear given adequate winter protection).

Therefore, it is important that this be a consideration prior to planting purple fountain grass, as the likelihood of its return each year in zones 6 or lower is slim to none. In fact, in cooler regions the plant is normally treated as an annual instead.

However, it is still possible to enjoy this plant year after year when grown in a container and brought indoors for overwintering. You can cut it back to about three inches (8 cm.) or so and then place it either in a sunny window in a cool area of the home or simply place it in your basement.

Keep the plant moist, not soggy, watering it about once a month. Once the threat of freezing weather and frost has passed in spring, you can set the purple fountain grass back outdoors.

II. How to Grow and Care

Sunlight

Most ornamental grasses prefer baking in full sunlight, especially the purple fountain grass. Purple fountain grass Pennisetum needs up to eight hours of full sun daily and can survive in the garden in light shade.

For containers growing indoors, please provide them with a sunny window to bask in the sun.

Temperature and Humidity

Purple fountain grass Pennisetum thrives in warm climates and is hardy in zones 9-11. It can tolerate some cold snaps but needs adequate winter protection in colder climates.

So, you can add a frost blanket to a s cold frame to rake your plants indoors grown in pots. Alternatively, you can grow them in the garden with temperatures down to 20°F as a perennial to cut back in early spring.

Keep potted plants in a cool area or at room temperature and water them, allowing the roots not to dry out during cold weather.

When the weather turns warmer, take a week to acclimate your grass, taking them outdoors during the day and returning them indoors at night.

Or enjoy the purple foliage in flower arrangements in colder climates grown as an annual.

Watering

When you plant purple fountain grass, it needs deep watering often until the roots become established. You can do this once or twice a week.

Still, allow the soil to dry between watering to prevent root rot. Once the roots are established, it is reasonably drought tolerant, but we recommend watering often in dry climates without rain. You may find your container-grown plants need a bit more watering.

Soil

Luckily, purple fountain grass isn’t too picky about its soil conditions. Loamy soil often provides the best results, but the plant can do well in many types of mixtures, so long as they’re well-draining.

Fertilizing

Fountain grass grows fairly well in poor soil, but fertilizer will boost its growth and provide the additional nutrients it needs when flowering. During that time (typically the summer), feed it monthly with a general-purpose, slow-release food according to the directions on the fertilizer’s label.

Planting Instructions

Growing purple fountain grass is best done in the fall or spring, but we recommend taking advantage of planting them in spring during the growing season.

Planting purple fountain grass is considered a growth habit as these plants reach 5 feet tall at mature height. Also, plant them five feet apart in a deep and wide hole to accommodate the roots.

Then water them well to become established.

Pruning

When it comes to maintenance, you will only prune them. You can snip away the dead foliage around the plant. Doing this helps increase airflow allowing the sunlight to reach all grass parts.

In cool areas, you can cut back the foliage in late winter. This is normally after the bloom time for new growth to appear in spring. Alternatively, you can trim away any dead to damaged foliage at any time of the year.

Propagation

Purple fountain grass can be propagated through division or seeds. The plants may readily self-seed in the garden, but root division is a faster and more reliable form of propagation than waiting for seeds. Division should be done in the fall after flowering when the plant is going into dormancy. Take these steps for propagating by division:

• Dig up the plant when it is going dormant.
• Use a clean, sharp cutting tool to cut it into two or more sections that contain healthy roots and leaves.
• Discard any rotten or dead plant matter and roots.
• Replant immediately and keep the soil moist as the division settles into its new home.

How to Grow From Seed

It’s easy to plant purple fountain grass from seed though it takes time to see results. Collect the seeds from the flowering stems when they’re dry, usually in the fall. Then take these steps to grow the grass from seeds:

• Take the whole stem and allow the flower stalk to dry out in a cool place. Collect the dry seeds from the flower plume.
• Surface sow the seeds in good potting soil with just a dusting of sand on top.
• Water until the container is evenly moist.
• Place the pot in a plastic bag or cover it with a plastic dome. Cut a couple of small slits on top of the bag so seeds can breathe.
• Once you have seedlings with two sets of true leaves, transplant them to larger pots.
• Harden off the plants in the spring and install them in prepared containers or beds.

Potting and Repotting

The beauty of this plant makes it a popular focal point in a mixed bed, and also in container gardens. You can mass several of the plants together to create a visually beautiful border or privacy screen.

Plant purple fountain grass in a pot with flowering plants or by itself. Make sure the container is large enough to accommodate the roots and that it has enough drainage holes so the soil will not become waterlogged. Place the containers in plenty of sunlight and move indoors when temperatures fall.

Overwintering

You can dig up the grass and place it in any type of planting container and bring it inside during the winter to survive. Cut the plants down to 3 inches tall.. They won’t look ornamental over the winter, but they should come back in the spring.

Place the container in a cool area or room where the temperature will not reach freezing. The plant’s shallow roots won’t tolerate freezing temperatures. Also, offer the plants a moderate amount of light during the winter. Keep the them watered, but not soggy, and do not let them dry out. Once the weather turns warmer in the spring, take a week to acclimate the plant by bringing it outdoors for a while during the day and indoors at night.

Pests and Diseases

Even if the purple fountain grass can grow in poor soil types and brighten the garden in late spring to winter, it is also resistant to most pests and diseases. It is drought tolerant to some extent, and deer do not enjoy munching on them.

But as with most plants, you can find some snails and slugs nibbling on the purple foliage, but they do not cause harm and are primarily cosmetic. Purple fountain grass can become susceptible to fungal diseases as it hides between the blades without enough air circulation.

So, prune them often and provide enough full sunlight to dry the foliage out.

III. Types of Purple Fountain Grass

Fountain grass has a variety of cultivars that each bring something different to the garden. Here are a few of the most popular.

• Pennisetum setaceum ‘Fireworks’: One cultivar of the purple fountain grass species, this plant has variegated leaves with burgundy in the middle and hot pink at the edges.
• P. alopecuroides ‘Burgundy Bunny’: A cultivar of a relatively cold-hardy species of fountain grass in the Pennisetum genus, this variety stands 16 inches tall. The foliage has hints of red in summer, but the color intensifies to a deep reddish-purple in fall.
• P. alopecuroides ‘Little Bunny’: Another cultivar of P. alopecuroides, ‘Little Bunny’ stands 12 inches tall with a slightly greater spread. This variety lacks the colorful foliage of ‘Burgundy Bunny’ but features buff-colored flowers.

IV. Uses and Benefits

Welcomed in any garden style, Purple Fountain Grass is a focal point wherever it is planted. It is versatile and can be used as a specimen plant, providing a dramatic effect in groups or en masse. It is ideal in borders, providing texture, color, and contrast, and looks impressive in containers. Efficient for softening driveways or courtyards too!